Sting sure is a member of The Police (9)
I believe the answer is:
constable
'member of the police' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'sting sure' is the wordplay.
'sting' becomes 'con' (synonyms).
'sure' becomes 'stable'.
'con'+'stable'='CONSTABLE'
'is a' acts as a link.
Can you help me to learn more?
(Other definitions for constable that I've seen before include "Did he have a brush" , "He painted" , "CARRY ON FILM" , "See 1" , "in blue?" .)