Fair method by judge (8)
I believe the answer is:
moderate
'fair' is the definition.
('moderate' can be similar in meaning to 'fair')
'method by judge' is the wordplay.
'method' becomes 'mode' (I've seen this before).
'by' says to put letters next to each other.
'judge' becomes 'rate' (rating is a kind of judging).
'mode'+'rate'='MODERATE'
(Other definitions for moderate that I've seen before include "Ordinary" , "Reduce" , "Dare me to (anag) - act as an arbitrator" , "Average; make less extreme" , "Become less extreme" .)