Tug sharply (4)
I believe the answer is:
yank
'tug sharply' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for yank that I've seen before include "Pull sharply" , "Sudden hard pull" , "Pull with a sudden movement" , "sudden 24D [DRAW] ?" , "Tug sharply - American" .)