Donkey's stealing heart from governess Grey (4)

I believe the answer is:

ages

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'donkey's stealing heart from governess grey' is the definition.
I can't judge whether this defines the answer.

'stealing heart from governess grey' is the wordplay.
'stealing heart from' suggests removing the centre.
'governess grey' becomes 'Agnes' (Agnes Grey is a novel by Anne Bronte).
'agnes' with its centre removed is 'AGES'.

Can you help me to learn more?

(Other definitions for ages that I've seen before include "A long time (colloq.)" , "Historic periods or prolonged time" , "Rock of - - (hymn)" , "Yonks" , "Sage (anag)" .)

I've seen this clue in The Times.

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