Charming about injury (4)
'injury' is the definition.
('harm' can be a synonym of 'injury')
'charming about' is the wordplay.
'about' indicates the answer is hidden within the clue.
'HARM' is hidden within 'charming'.
(Other definitions for harm that I've seen before include "Short-long metric feet", "Hurt, injure", "Trials, exams", "Wound", "Hurt, maim".)