Individual emulates retiring judge (8)
I believe the answer is:
separate
'individual' is the definition.
'emulates retiring judge' is the wordplay.
'emulates' becomes 'apes' (I've seen this in another clue).
'retiring' is a reversal indicator.
'judge' becomes 'rate' (rating is a kind of judging).
'apes' in reverse letter order is 'sepa'.
'sepa'+'rate'='SEPARATE'
(Other definitions for separate that I've seen before include "divorce" , "Unconnected" , "Distinct or discrete" , "Move" , "Individual and distinct" .)