How much play should there be in the rear wheels? I know theres meant to be a little due to the way its all designed etc

Basically over large potholes the n/s rear left wheel sounds knocks. Rear is polybushed, everythings tight and solid, brakes etc are fine, just wondered if there was slightly too much play it would make the knock noise everytime it hit a pothole/solid bump in the road?

cheers