Poins is taken in by girl's facial expression of disgust (7)
I believe the answer is:
grimace
'facial expression of disgust' is the definition.
(I've seen this before)
'poins is taken in by girl's' is the wordplay.
'poins is' becomes 'I'm' (where the crossword setter is 'Poins').
'taken in by' is an insertion indicator.
'girl' becomes 'grace' ().
'im' put into 'grace' is 'GRIMACE'.
(Other definitions for grimace that I've seen before include "Wry look" , "Pained expression" , "Distorted facial expression" , "displeasure" , "Twisted facial expression" .)