Spar with graduates boxing in street (8)
I believe the answer is:
mainmast
'spar' is the definition.
(I know that mainmast is a type of mast)
'graduates boxing in street' is the wordplay.
'graduates' becomes 'MA MA' (more than one holder of a Master of Arts degree).
'boxing' indicates putting letters inside ('box' can mean contain, as in to put in a box).
'street' becomes 'st' (abbreviation).
'mama' enclosing 'in' is 'mainma'.
'mainma'+'st'='MAINMAST'
'with' is the link.
(Other definitions for mainmast that I've seen before include "hoist sail on this" , "rigging for a dandy" .)