LOL, either the clown is going to kill the clam or more likely, the clam is going to have a big snack!

Seriously though, it isn't good for the clam. May damage it to where other predetors pick on it and eventually kill it. It may just stress it to the point it weakens and dies also. Either try finding the clown an anemone to host in or remove it for awhile and hope it learns to play well with others.