Cockney injured with a knife? (5)
I believe the answer is:
armed
I believe this clue is a double definition.
'cockney injured' is the first definition.
('harmed' - similar in meaning - said with a cockney accent, dropping the 'H')
'with a knife?' is the second definition.
(carrying a knife)
(Other definitions for armed that I've seen before include "Munitioned" , "Carrying a weapon" , "Prepared for attack" , "unlike the Venus of Milo" , "Given weapons" .)