Gridiron official, for short (3)
I believe the answer is:
ref
'gridiron official for short' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ref that I've seen before include "In brief, he controls a soccer match" , "Football's whistler" , "Football official (colloq.)" , "Middleman needing cards" , "One traditionally in black" .)