Gain an advantage by trickery (4,1,4,3)
I believe the answer is:
pull a fast one
'gain an advantage by trickery' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for pull a fast one that I've seen before include "Play a sly trick" , "draw with ace sprinter?" , "act unscrupulously" , "Gain an advantage by trickery" , "Cheat" .)