Start-of-year return for corrupt concierge (7)

I believe the answer is:

janitor

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'concierge' is the definition.
(thesaurus)

I cannot understand how the rest of the clue works.

(Other definitions for janitor that I've seen before include "(In Scotland) school caretaker" , "One employed to clean and maintain a building" , "Caretaker or doorkeeper" , "Caretaker (mainly US)" , "Person looking after building" .)

I've seen this clue in The Times.

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