Fight arbiter (3)
I believe the answer is:
ref
'fight arbiter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ref that I've seen before include "In brief, he controls a soccer match" , "Middleman needing cards" , "Sports official (abbrev.)" , "In brief, a soccer controller" , "One traditionally in black" .)