I've had clown's literally refuse to move from their nem, it's actually how I removed my last set. There may be a small acclimation period as some clown's usually only host certain nem's in the wild but in our tanks, they sometimes take what they can get. [smilie=lol.gif] Here's a list of which clown's host which anemone naturally.
http://www.amdareef.com/ho_anemones.htm
Cheers,