Judge enters for a favour (6)
I believe the answer is:
prefer
'favour' is the definition.
(I know that favour can be written as prefer)
'judge enters for a' is the wordplay.
'judge' becomes 'ref'.
'enters' is an insertion indicator.
'for a' becomes 'per' ('per' can mean 'for each' person or 'for a' person).
'ref' put into 'per' is 'PREFER'.
(Other definitions for prefer that I've seen before include "as one may with charges" , "Promote; like better" , "Value more highly" , "Like one better than another" , "Like (something) better than another" .)