Fight in 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 before)
'in' acts as a link.
(Other definitions for spar that I've seen before include "Raps with large timber" , "Raps with strong pole" , "Box - mineral - rod" , "possibly rigged" , "Close friend" .)