Winning with Neath or Garryowen? (2-3-5)

I believe the answer is:

up-and-under

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'garryowen?' is the definition.
I can't judge whether this defines the answer.

'winning with neath' is the wordplay.
'winning' becomes 'up' (eg being up at half time in football).
'with' becomes 'and'.
'neath' becomes 'under' (I am not sure about this - if you are sure you should believe this answer much more).
'up'+'and'+'under'='UP-AND-UNDER'

'or' acts as a link.

Can you help me to learn more?

I've seen this clue in The Times.

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