I usually use nix develop to work on a specific project. I'd like to see how well CLion could work with Nix but I am not sure how to make these two work well with each other.
I have found this gist so far but CLion complains that that the files don't exist when I select them from the settings as instructed.
My main tip would be to launch CLion from within nix develop. I use nohup idea-ultimate nosplash . &>/dev/null & disown for IDEA to properly silence the output and detach from the terminal. At that point CLion will hopefully pick up the tools which are on $PATH.