Not that odd number in Sevenoaks! (4)

I believe the answer is:

even

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'not that odd number' is the definition.
I can't judge whether this defines the answer.

'in sevenoaks' is the wordplay.
'in' indicates a hidden word.
'EVEN' is hidden within 'sevenoaks'.

Can you help me to learn more?

(Other definitions for even that I've seen before include "Steady or smooth" , "Smooth, level" , "Short joke" , "Commensurate" , "Yet; level" .)

I've seen this clue in the Evening Standard.

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