Skillful at trickery (3)
I believe the answer is:
sly
'skillful at trickery' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sly that I've seen before include "'Crafty, cunning (3)'" , "Cunning, foxy" , "Cunning; surreptitious" , "Artful" , "Doing things in unpleasant and secret way" .)