Sword injured girl (7)
I believe the answer is:
cutlass
'sword' is the definition.
(I've seen this before)
'injured girl' is the wordplay.
'injured' becomes 'cut' ('cut' can be similar in meaning to 'injured').
'girl' becomes 'lass' (lass is a kind of girl).
'cut'+'lass'='CUTLASS'
(Other definitions for cutlass that I've seen before include "Pirate sword" , "Old sailor's sword" , "Pirate's weapon" , "Short broad sword" , "Sword formerly used by sailors" .)