Anemones will do just fine without clowns, and clowns will do just fine without anemones. Sometimes the clown will bring the anemone food and feed it, maybe that's what you heard about. But that doesn't always happen either. Anyways, an anemone does not need a clown to thrive and vice versa.
If a clown tries to be hosted by a coral, the coral will usually close up and stay closed, because the clown irritates them. So clowns in flowerpots and other corals may look cool, but it's not healthy for the coral. My female tomato clown has killed several of my corals, including a flowerpot, alveopora, hammer, torch and 3 plate corals from trying to be hosted in it.