Type of crime committed by a prisoner? (6,3)

I believe the answer is:

inside job

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'type of crime' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for inside job that I've seen before include "breach of trust" , "Crime of one hired before" , "Crime aided by employees" , "Crime with help" , "Sort of crime" .)

I've seen this clue in The Guardian.

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