Linger furtively (4)
I believe the answer is:
lurk
'linger furtively' 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 "Skulk, hide" , "Linger around furtively" , "Read (but take no part in) online chat" , "Wait in hiding to attack" , "Wait in ambush" .)