Look good with weapon (6)
I believe the answer is:
glance
'look' is the definition.
(glancing is a kind of looking)
'good with weapon' is the wordplay.
'good' becomes 'g' (abbreviation).
'with' means one lot of letters go next to another.
'weapon' becomes 'lance' (lance is a kind of weapon).
'g'+'lance'='GLANCE'
(Other definitions for glance that I've seen before include "Momentary look" , "Look quickly at -- cricket stroke" , "Look briefly or bounce off" , "batsman's shot" , "Batting stroke" .)