Feature about round rope loop (5)
I believe the answer is:
noose
'rope loop' is the definition.
(I've seen this before)
'feature about round' is the wordplay.
'feature' becomes 'nose' (a facial feature).
'about' means one lot of letters goes inside another.
'round' becomes 'o' (o is a circular letter).
'nose' going around 'o' is 'NOOSE'.
(Other definitions for noose that I've seen before include "Circular loop" , "Cord snare" , "Catch" , "This exemplifies marriage for some" , "Loop of cord" .)