Spy a polite man? (5)

I believe the answer is:

agent

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'spy' is the definition.
(secret agent)

'a polite man?' is the wordplay.
'polite man?' becomes 'gent' (gent is a kind of man. I am not sure about the 'polite' bit.).
'a'+'gent'='AGENT'

Can you help me to learn more?

(Other definitions for agent that I've seen before include "Instrument" , "Performer's manager" , "Spy; service provider" , "One acting on behalf of another" , "Vehicle" .)

I've seen this clue in The Sun.

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