Secure again (5)
I believe the answer is:
retie
'secure again' is the definition.
('tie' is an answer for 'secure' so perhaps 'retie' is OK for 'secure again')
This is the entire clue.
(Other definitions for retie that I've seen before include "Link up again" , "make another knot" , "Make knot or bow again" , "restore connection" , "Bind again" .)