Old sword caused injury to young woman (7)
I believe the answer is:
cutlass
'old sword' is the definition.
(I've seen this in another clue)
'injury to young woman' is the wordplay.
'injury' becomes 'cut' (cut is a kind of injury).
'to young woman' becomes 'lass' (informal term for a young woman).
'cut'+'lass'='CUTLASS'
'caused' acts as a link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for cutlass that I've seen before include "Pirate's weapon" , "Piratical sword" , "Curved sailors' sword" , "Curved, one-edged sword" , "could hurt one, in the main" .)