It's not really about the clown "growing out of it" but I guess what you're asking is, will she eventually develop a coating that mimics the anemone so that she won't get stung? The answer is, usually.
However apparently there are different abilities for different clowns to match certain anemones. For instance, Haddonis can sometimes see through the disguise of a percula or occelaris and suddenly make a snack of a clown it had previously hosted. So some clowns don't always work it out if the anemone isn't their natural host.