Lie in wait (4)
I believe the answer is:
lurk
'lie in wait' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lurk that I've seen before include "Wait furtively" , "Lie in wait" , "Behave in a sneaky and secretive manner" , "Hide menacingly" , "View an online forum without contributing" .)