Winds round reel (5)
I believe the answer is:
spool
'reel' is the definition.
('spool' can be a synonym of 'reel')
'winds round' is the wordplay.
'winds' becomes 'loops' (looping is a kind of winding).
'round' says the letters should be written backwards.
'loops' backwards is 'SPOOL'.
(Other definitions for spool that I've seen before include "Film reel; wind" , "Cylinder for winding film etc" , "Ribbon holder" , "Loops around with reel" , "On which film is wound" .)