Weapon injured young woman (7)
I believe the answer is:
cutlass
'weapon' is the definition.
(cutlass is a kind of weapon)
'injured young woman' is the wordplay.
'injured' becomes 'cut' (similar in meaning).
'young woman' becomes 'lass' (informal term for a young woman).
'cut'+'lass'='CUTLASS'
(Other definitions for cutlass that I've seen before include "Sharp weapon" , "Curved, one-edged sword" , "Short broad sword" , "Sailor's blade" , "Old sailor's sword" .)