Twisted, as a grin (3)
I believe the answer is:
wry
'twisted as a grin' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for wry that I've seen before include "Mockingly humorous" , "Drily humorous" , "Dry and mocking, or bent out of shape" , "Crooked - droll" , "Perverse" .)