A clique protecting others is impressive (9)
I believe the answer is:
arresting
'impressive' is the definition.
('arresting' can be similar in meaning to 'impressive')
'a clique protecting others' is the wordplay.
'clique' becomes 'ring' (I've seen this in other clues).
'protecting' means one lot of letters goes inside another.
'others' becomes 'rest' (I've seen this before).
'ring' going around 'rest' is 'rresting'.
'a'+'rresting'='ARRESTING'
'is' is the link.
(Other definitions for arresting that I've seen before include "Lovely" , "remarkable" , "job of a police officer" , "spectacular" , "Police officers are doing it regularly" .)