The problem with introducing an anemone into a tank with corals is that it will move to find a good spot for itself. It may hit your corals, which may sting it, or vice versa, resulting in the possible death of one or the other.
Anemones need good lighting, and meaty foods, but prior to getting one, you need to find out what kind of clown you have. This is very important, because not all clowns are compatible with all anemones.
Also, even if all of that is taken care of, you are still taking a chance in that there is no guarantee that your clown will actually take to the anemone. Some do not.
I am all for anemones - have a nice BTA myself. There are just a lot of factors to consider.