Nope, the cleaner wrasse will get far too big and active. A pair of clownfish will almost max the tank out themselves, a neon goby would be a nice addition if you want some blue with them. If you want larger wrasses and the like, I would upgrade to more like a 50 gallon.
There are also some small wrasses that would do OK in a 20 like the pink-streaked wrasse or possum wrasses.