I remember reading a post about an anemone crab that was hanging out in a nem (BTA I think), and there was a clown pair in the tank -- the clowns did not like it one bit and one day they grabbed the crab and brought him to a fish that would eat it -- crab problem solved!
I don't remember all the details but that's the essence of it.
I was impressed that not only did the clowns know exactly what they want, but they were creative about the solution!