[Ydiss]

No, there's no cheat to make yourself invisible, it's a bug.

Sadly, you've accused him of cheating when he wasn't and probably meritted your banning.

It's a glitch where any one player can appear invisible to you and you alone - It's totally a local error. To fix it simply type "vid_restart" in the console and it should fix it - failing that reconnecting will fix the error (for you or the person who is invisible).

Your friend who spectated him would have been able to see him so it would seem that you were making it up.

Sorry, that's all I can do to help you - if you really want to be in the clan still then I'd suggest contacting them and saying sorry and that you now know what it was that was causing it.

Other than that, they were well within their rights to kick you really - Never accuse or confront someone of cheating (especially a clan mate, lol) until you are absolutely 100% sure.