Interrogate a man? (8,4)

I believe the answer is:

question mark

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

'interrogate a man?' is the definition.
I can't judge whether this defines the answer.

'interrogate a man?' is the wordplay.
'interrogate' becomes 'question' (synonyms).
'a man?' becomes 'mark' ().
'question'+'mark'='QUESTION-MARK'

Can you help me to learn more?

(Other definitions for question mark that I've seen before include "Not believe the gospel" , "What ends this" , "Expression of uncertainty" , "Query" .)

I've seen this clue in The Irish Independent.

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