Policeman from Vice vetted criminal, one very withdrawn (9)

I believe the answer is:

detective

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'policeman' is the definition.
(detective is a kind of policeman)

I can't explain the remainder of the clue.

(Other definitions for detective that I've seen before include "such as Chesterton's father" , "Policeman, say" , "Expert solver of clues" , "Investigating policeman" , "Sleuth" .)

I've seen this clue in The Telegraph.

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