Strange attire on bent bar judge (9)
I believe the answer is:
arbitrate
'judge' is the definition.
(thesaurus)
'strange attire on bent bar' is the wordplay.
'strange' is an anagram indicator.
'on' is a charade indicator (letters next to each other).
'bent' is an anagram indicator.
'attire' anagrammed gives 'itrate'.
'bar' anagrammed gives 'arb'.
'itrate' put after 'arb' is 'ARBITRATE'.
(Other definitions for arbitrate that I've seen before include "Mediate" , "Adjudge" , "judge" , "Decide" , "Act between disputing parties" .)