Judge mishandled rare cases a little (7)
I believe the answer is:
arbiter
'judge' is the definition.
(I've seen this in another clue)
'mishandled rare cases a little' is the wordplay.
'mishandled' indicates anagramming the letters.
'cases' indicates putting letters inside (forms a case around).
'a little' becomes 'bit' (a small bit).
'rare' is an anagram of 'arer'.
'arer' placed around 'bit' is 'ARBITER'.
(Other definitions for arbiter that I've seen before include "Judge, adjudicator" , "He'll decide" , "Ref" , "One appointed to settle a dispute" , "Referee or judge of rarebit" .)