Fight in the yard (4)
I believe the answer is:
spar
I believe this is a double definition.
'fight' is the first definition.
(sparring is a kind of fighting)
'yard' is the second definition.
(I've seen this in another clue)
'in the' is the link.
(Other definitions for spar that I've seen before include "Crystal - box" , "dispute" , "Box for practice" , "possibly rigged" , "Box without punching hard" .)