Hurtful extract (7)
I believe the answer is:
cutting
I believe this clue is a double definition.
'hurtful' is the first definition.
(I've seen this before)
'extract' is the second definition.
(I know that cutting is a type of extract)
(Other definitions for cutting that I've seen before include "Keen" , "Of a comment, pointed" , "piece used for plant propagation" , "Sarcastic - excavation for railway etc" , "Barbed" .)