Adding a simple clock to a GUI

I have some code for a very generic/blank GUI with some labels and pushbuttons and an LCD widget. I also have some code for a separate window which just uses an LCD widget to display the time. My question is how do I insert to code for the clock into the generic GUI code to make that LCD widget display the time?

from PyQt5.QtCore import QTime, QTimer
from PyQt5.QtWidgets import QApplication, QLCDNumber
class DigitalClock(QLCDNumber):

    def __init__(self, parent=None):
        super(DigitalClock, self).__init__(parent)
        self.setSegmentStyle(QLCDNumber.Filled)
        timer = QTimer(self)
        timer.timeout.connect(self.showTime)
        timer.start(1000)
        self.showTime()
        self.setWindowTitle("Digital Clock")
        self.resize(150, 60)

    def showTime(self):
        time = QTime.currentTime()
        text = time.toString('hh:mm')
        if (time.second() % 2) == 0:
            text = text[:2] + ' ' + text[3:]
        self.display(text)

if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    clock = DigitalClock()
    clock.show()
    sys.exit(app.exec_())

That's the code for the simple clock and I want to insert that into the following to make the LCD widget display the time like this one does:

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_mainWindow(object):
    def setupUi(self, mainWindow):
        mainWindow.setObjectName("mainWindow")
        mainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(mainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.Clock = QtWidgets.QWidget(self.centralwidget)
        self.Clock.setGeometry(QtCore.QRect(60, 420, 120, 80))
        self.Clock.setObjectName("Clock")
        self.DigitalClock = QtWidgets.QLCDNumber(self.centralwidget)
        self.DigitalClock.setGeometry(QtCore.QRect(110, 190, 64, 23))
        self.DigitalClock.setDigitCount(8)
        self.DigitalClock.setObjectName("DigitalClock")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(100, 60, 75, 23))
        self.pushButton.setObjectName("pushButton")
        self.pushButton_2 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_2.setGeometry(QtCore.QRect(100, 110, 75, 23))
        self.pushButton_2.setObjectName("pushButton_2")
        self.pushButton_3 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_3.setGeometry(QtCore.QRect(100, 150, 75, 23))
        self.pushButton_3.setObjectName("pushButton_3")
        self.pushButton_4 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_4.setGeometry(QtCore.QRect(230, 60, 75, 23))
        self.pushButton_4.setObjectName("pushButton_4")
        self.pushButton_5 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_5.setGeometry(QtCore.QRect(220, 100, 75, 23))
        self.pushButton_5.setObjectName("pushButton_5")
        self.pushButton_6 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_6.setGeometry(QtCore.QRect(230, 150, 75, 23))
        self.pushButton_6.setObjectName("pushButton_6")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(20, 60, 47, 13))
        self.label.setObjectName("label")
        self.label_2 = QtWidgets.QLabel(self.centralwidget)
        self.label_2.setGeometry(QtCore.QRect(20, 120, 47, 13))
        self.label_2.setObjectName("label_2")
        self.label_3 = QtWidgets.QLabel(self.centralwidget)
        self.label_3.setGeometry(QtCore.QRect(20, 160, 47, 13))
        self.label_3.setObjectName("label_3")
        mainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(mainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 21))
        self.menubar.setObjectName("menubar")
        mainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(mainWindow)
        self.statusbar.setObjectName("statusbar")
        mainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(mainWindow)
        QtCore.QMetaObject.connectSlotsByName(mainWindow)

    def retranslateUi(self, mainWindow):
        _translate = QtCore.QCoreApplication.translate
        mainWindow.setWindowTitle(_translate("mainWindow", "Sim Monitor"))
        self.pushButton.setText(_translate("mainWindow", "PushButton"))
        self.pushButton_2.setText(_translate("mainWindow", "PushButton"))
        self.pushButton_3.setText(_translate("mainWindow", "PushButton"))
        self.pushButton_4.setText(_translate("mainWindow", "PushButton"))
        self.pushButton_5.setText(_translate("mainWindow", "PushButton"))
        self.pushButton_6.setText(_translate("mainWindow", "PushButton"))
        self.label.setText(_translate("mainWindow", "TextLabel"))
        self.label_2.setText(_translate("mainWindow", "TextLabel"))
        self.label_3.setText(_translate("mainWindow", "TextLabel"))


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    mainWindow = QtWidgets.QMainWindow()
    ui = Ui_mainWindow()
    ui.setupUi(mainWindow)
    mainWindow.show()
    sys.exit(app.exec_())

Simple solution:

Assuming that the first file is called DigitalClock.py and the second main.py then it is only necessary to add the import to main.py and change the line that the QLCDNumber creates:

main.py

from DigitalClock import DigitalClock
# ...
self.DigitalClock = DigitalClock(self.centralwidget) # QtWidgets.QLCDNumber(self.centralwidget)

Long solution:

Promote the QLCDNumber to use the DigitalClock, you could take the guide of this other answer where you would exchange QVideoWidget with DigitalClock and PyQt5.QtMultimediaWidgets with DigitalClock.

The other way is to create a widget plugin so that it can be used directly in Qt Designer.