Mouses only have 5 buttons + scroll wheel/scroll wheel click, any more are remapped keyboard buttons. You remap the buttons in the software to a “keyboard button” then you assign that keyboard button in clique to what you want to cast.
I believe clique works on mouseovers. So you can technically bind 2 keys to one button. Say your remapped “8” key is a button on your mouse. You can map "8’ to say healing touch inside clique, but then assign some self cast ability you have so when you aren’t over the frames it casts your self-cast.
I do this with my priest. Prayer of healing is mapped to “2” on the keyboard when over the frames, but outside the frames it casts mindblast