Noose (4)
I believe the answer is:
loop
'noose' is the definition.
(I know that noose is a more specific form of loop)
This is all the clue.
(Other definitions for loop that I've seen before include "flying stunt" , "Curve that bends round and crosses itself" , "not informed one's out of it" , "Oval shape" , "Contraception device - hearing aid" .)