Fair — punishment (4)
I believe the answer is:
fine
This clue is a double definition.
'fair' is the first definition.
(I've seen this before)
'punishment' is the second definition.
(I know that fine is a type of fine)
(Other definitions for fine that I've seen before include "Capital - punishment" , "Very good; penalty" , "Sunny -- penalty" , "Fee payable for misdemeanour" , "First-rate - punishment" .)