Sounds like Armagh might do this during Ulster Championship? Oh, that won't happen! (8)

I believe the answer is:

playdown

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'this during ulster championship? oh that won't happen' is the definition.
The definition suggests a singular noun which matches the answer.

'sounds like armagh might do' is the wordplay.
I cannot really see how this works, but
'like' could be 'y' (similar in meaning) and 'y' is present in the answer.
'do' is within the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Irish Times.

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