Argue about English weapon (5)
I believe the answer is:
spear
'weapon' is the definition.
(spear is a kind of weapon)
'argue about english' is the wordplay.
'argue' becomes 'spar' (sparring is a kind of arguing).
'about' indicates putting letters inside.
'english' becomes 'e' (abbreviation).
'spar' going around 'e' is 'SPEAR'.
(Other definitions for spear that I've seen before include "Pole with pointed end" , "asparagus for example" , "Lance" , "Long pointed weapon" , "Stabbing, throwing, weapon" .)