Finished John? Stephen failing to notice? (11)

I believe the answer is:

overlooking

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'failing to notice?' is the definition.
(I've seen this before)

'finished john? stephen' is the wordplay.
'finished' becomes 'over' (over can mean finished or ended).
'john? stephen' becomes 'looking' (I can't justify this - if you can you should give a lot more credence to this answer).
'over'+'looking'='OVERLOOKING'

Can you help me to learn more?

(Another definition for overlooking that I've seen is " Failing to notice".)

I've seen this clue in the Sydney Morning Herald.

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