Diarist's manner not extremely honest (4,5)

I believe the answer is:

anne frank

'diarist's' is the definition.
(author of The Diary of a Young Girl)

'manner not extremely honest' is the wordplay.
'not extremely' says to take the centre (remove the letters on the extremes of the word).
'honest' becomes 'frank' (similar in meaning).
The centre of 'manner' is 'anne'.
'anne'+'frank'='ANNE FRANK'

(Another definition for anne frank that I've seen is " Jewish girl who wrote famous diary in WW2".)

I've seen this clue in The Guardian.

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