Bind securely (4)
I believe the answer is:
lash
'bind securely' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lash that I've seen before include "Beat severely with a whip" , "Sweep" , "Fasten with rope; whip" , "Beat; fasten with cord" , "cat hair?" .)