Fix, as a knot (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
retie
'fix as a knot' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for retie that I've seen before include "restore connection" , "Make knot or bow again" , "Bind again" , "Link up again" , "make another knot" .)