Wait in the shadows (4)
I believe the answer is:
lurk
'wait in the shadows' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lurk that I've seen before include "Behave in a sneaky and secretive manner" , "Skulk, hide" , "Lie hidden" , "Lie in ambush" , "Lie in wait" .)