Age of enlightenment? (3)

I believe the answer is:

ten

'age' is the definition.
(ten years old is an age)

'of enlightenment?' is the wordplay.
'of' says the answer is hidden in the clue.
'TEN' can be found hidden inside 'enlightenment'.

(Other definitions for ten that I've seen before include "Very young" , "X-WORD" , "Dudley Moore/Bo Derek film" , "PM's address, Downing St" , "Roman numeral X" .)

I've seen this clue in the Evening Standard.

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