My clowns are hosting my frogspawn. They don't actually go in it, they sleep under it, feed it and are pretty territorial around it. Unfortunately, they have the black marks on their fins that come with hosting something other than anenomes. If I remember correctly, they did try to go in it at first but I think they got stung.
Here's a pic of my female swimming above the frog. Like sharkbait said, I don't know how common it is, depends on your clowns.
Good luck!
