Kid is one making bishop look small and stupid (5)
I believe the answer is:
silly
'stupid' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
(Other definitions for silly that I've seen before include "Idiotic" , "near the batsman" , "Stupid" , "Inane; very close (fielder)" , "Ludicrous, foolish" .)