Fastens, binds (4)
I believe the answer is:
ties
This clue is a double definition.
'fastens' is the first definition.
(tying is a kind of fastening)
'binds' is the second definition.
('tie' can be a synonym of 'bind')
(Other definitions for ties that I've seen before include "Fastens with a knot" , "Attaches, knots" , "Binds with male neckwear" , "Connects" , "Items of neckwear" .)