Singer knocking bishop out, the idiot (3)
I believe the answer is:
ass
'the idiot' is the definition.
(both can mean a stupid person)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for ass that I've seen before include "Dipstick" , "Braying animal" , "Wally" , "Horse-type animal" , "Hardy and sure-footed animal" .)