Most clans don't want an outside player representing them , it cheapens any success that they may have. Also as the outside player doesn't have any affiliation to the clan there is no guarantee they will try there hardest.
So if your really want to play you are going to have to look at some of the least established clans performing. World league are quite new and might allow you to play for them.
) - There leader
TL;DR just wait until a CL that you can play for a clan you actually care about.