If you are looking to get an anemone make sure your tank is mature. I would have to say wait at least 6 months. I have much experience with the trial and error of keeping them. The best anemone to get for a maroon clown is an BTA. They are also among the hardiest anemones you could get. I have a maroon clown and he enjoys the BTA. He has hosted in a green bubble tip and a rose bubble tip after the green one was lost to an intake. Please be careful when purchasing one, they are very sensitive to little changes and need great water quality.
Maroon Clowns are very hard to mate. I had a nice Maroon Pair for a while until my take had a spike and I lost the Smaller one. I have lost several clowns in the past trying to mate them. You may want to try to find a pre mated pair. Maroon clowns also had problems with other newly introduced clowns in my tank before. The Maroons I had loved a Colt Coral I had in the Tank and lived in it like an Anemone.
Thanks for all the info. This forum is really good to have for us newbies. I almost bought a BTA and a Maroon clownfish but decided to ask about it on this site first. I purchased a purple sea slug, and after I looked it up on this forum and found out that it is almost impossible to keep alive. It did die after only a few days and so now I don't make any purchases until I research it here on this site. So I probably won't get a sea anemone for now. Thanks again.