Boxer's plane? (7)
I believe the answer is:
fighter
This clue is a double definition.
'boxer's' is the first definition.
(thesaurus)
'plane?' is the second definition.
(fighter is a kind of plane)
(Other definitions for fighter that I've seen before include "Freight (anag.)" , "Military jet" , "Boxer; warrior" , "Warplane" , "Combatant, battler" .)