Police officer in bust making fellow tense initially (9)

I believe the answer is:

detective

I'm a little stuck... Click here to teach me more about this clue!

'police officer' is the definition.
(I know that detective is a type of police officer)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for detective that I've seen before include "Sleuth" , "Expert solver of clues" , "Criminal investigator" , "police officer" , "Public or private investigator" .)

I've seen this clue in The Independent.

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