Try dropping unknown firearm, not given to wounding (9)
I believe the answer is:
traumatic
'wounding' is the definition.
(synonyms)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for traumatic that I've seen before include "Deeply disturbing" , "Emotionally shocking" , "Deeply distressing" , "Psychologically painful" , "Direly shocking" .)