Judge treats criminal wise men first (10)
I believe the answer is:
magistrate
'judge' is the definition.
(I know that judge can be written as magistrate)
'treats criminal wise men first' is the wordplay.
'criminal' is an anagram indicator.
'wise men' becomes 'magi' (the three wise men from the nativity).
'first' says to put letters next to each other.
'treats' is an anagram of 'strate'.
'strate' after 'magi' is 'MAGISTRATE'.
(Other definitions for magistrate that I've seen before include "Justice of the peace" , "Capital of Ethiopia" , "JP" , "Court officer" , "Dispenser of justice" .)