any fish that mainly eats sand critters are tricky customers to deal with, and not the best for an only sand cleaning role. stuff that eats both sand life and is fine bottom feeding tend to be best for it is current idea of the rule of thumbSome bristleworms are also good at sand sifting (though most hide away in rockwork). If you have none in your tank, you could buy some on eBay, but I have always had them hitchhike on live rock.
Sand dollars are technically an option, but they deplete sandbed biodiversity and subsequently starve, like Horseshoe crabs and Sand-sifting starfish. You could try feeding them sinking pellets, but I would just avoid these three sand-sifters in most cases.
Finally, Cleaner clams require frequent phytoplankton dosage, so they would also not be ideal.