It's somewhat circular, like a ring in the nose (5)
I believe the answer is:
noose
'it's somewhat circular' is the definition.
I can't judge whether this defines the answer.
'ring in the nose' is the wordplay.
'ring' becomes 'o' (letter resembling a ring).
'in' indicates putting letters inside.
'o' inserted into 'nose' is 'NOOSE'.
'like a' acts as a link.
Can you help me to learn more?
(Other definitions for noose that I've seen before include "Hangman's knot" , "Looped rope" , "Hangman's rope" , "Loop - snare" , "Cord snare" .)