Sword? I’m the very thing involved in evidence of wound (8)
I believe the answer is:
scimitar
'sword?' is the definition.
(scimitar is a kind of sword)
'i'm the very thing involved in evidence of wound' is the wordplay.
'the very thing' becomes 'it' ('that's it!').
'involved in' means one lot of letters goes inside another.
'evidence of wound' becomes 'scar' (a wound might leave a scar).
'im'+'it'='imit'
'imit' inserted within 'scar' is 'SCIMITAR'.
(Other definitions for scimitar that I've seen before include "I'm racist, owning an oriental sword" , "Eastern sword" , "Curved oriental sabre" , "Type of sword with curved blade" , "sharp weapon" .)