A long time coming from Lake Ontario (3)

I believe the answer is:

eon

'a long time' is the definition.
(I know this)

'coming from lake ontario' is the wordplay.
'coming from' indicates a hidden word.
'EON' is hidden within 'lake ontario'.

(Other definitions for eon that I've seen before include "Long period of time" , "Very long age" , "Geological period" , "Vast period" , "plenty of time" .)

I've seen this clue in The Irish Independent.

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