Attack in boxing contest (4)
I believe the answer is:
bout
I believe this is a double definition.
'attack' is the first definition.
(I've seen this before)
'boxing contest' is the second definition.
(a bout is a boxing match)
'in' acts as a link.
(Other definitions for bout that I've seen before include "Spell - boxing match" , "Attack (of illness)" , "Fight; instance of illness" , "Fit" , "Spell of eg drinking" .)