Set a time apart for judge (8)
I believe the answer is:
estimate
'judge' is the definition.
(estimating is a kind of judging)
'set a time apart' is the wordplay.
'apart' indicates anagramming the letters (the word is broken apart).
'set'+'a'+'time'='setatime'
'setatime' anagrammed gives 'ESTIMATE'.
'for' is the link.
(Other definitions for estimate that I've seen before include "Judge the worth of" , "Assess value" , "approximate price" , "Reckon, judge" , "Rough cost" .)