Hi,
Clown fish eat almost anything.
However, if u buy from lfs.
Then it takes time for it to get use of your tank environment.
They will start eating soon, if there are other fishes, as they will follow the rest of the pact.
Try those pallet food that sink.or stick to the tank wall.
They usually do not know how to eat from the surface (It takes time).
That's why always adopt or buy from reefer.