I have two false perc happily living in a big BTA. Do they really need one? Not really, I've had clowns hosted by frogspawn, powerheads, rocks, glass in the corner.. lol they really are odd creatures.
In the long term if an anemone works for your tank they clowns would like it but it is not really needed.
That being said, 'nems are hard creatures to keep alive and happy, they need a well established mature tank to keep them properly. If you are just starting out the tank you should consider letting the tank mature for a while before you add an anemone to the stocking plans
