there really isn't a starter anemone for say , they are a delicate invert to maintain in a fairly new tank they wont do well.
your tank would need to be matured about a year for a nem .
lighting is another thing to consider for a nem they require strong lighting .
the florescence's on your tank wouldn't provide enough light .
as for your clown he will host about anything . make a small cave with a overhang .
I bet he will take ownership and host his cave , he will burrow out a hole were he will spend most of his time .
I have 2 clowns they love there cave they are constantly cleaning out any shells or rocks they find . it;s actually a fun experience seeing how they keep things clean .
If your looking to keep your tank as a FOWLR
your lighting is ok for what you have .
if you ever decide to go REEF that would be when you would need to upgrade your lighting.