Sly trick (4)
I believe the answer is:
wile
'sly trick' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for wile that I've seen before include "Coax - pleasing artifice" , "Trick, stratagem" , "Chicanery" , "Artfulness" , "Cunning ruse" .)