Peacekeepers' secretary-general perhaps not confirmed (10)

I believe the answer is:

unofficial

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'peacekeepers' secretary-general perhaps' is the definition.
I can't tell whether this definition defines the answer.

'not confirmed' is the wordplay.
'not' becomes 'un' (prefix meaning 'not').
'confirmed' becomes 'official' (similar in meaning).
'un'+'official'='UNOFFICIAL'

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(Other definitions for unofficial that I've seen before include "off the record" , "description of Grantchester's English rose" , "Not confirmed by authority" , "Unauthorised" .)

I've seen this clue in The Telegraph.

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