An inside job? (6,7)
I believe the answer is:
secret service
'an inside job?' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'inside job?' is the wordplay.
'inside' becomes 'secret' (synonyms).
'job?' becomes 'service' (service is a kind of job).
'secret'+'service'='SECRET SERVICE'
Can you help me to learn more?
(Other definitions for secret service that I've seen before include "MI5 or MI6 (informal)" , "Hush-hush organisation" , "Spying agency" , "Government department involved in espionage" , "Spies' department" .)