The "Auld Mug" - Ace Ceramics muddling order up (8,3)

I believe the answer is:

america's cup

I'm a little stuck... Click here to teach me more about this clue!

'the auld mug ace' is the definition.
The definition suggests a singular noun which matches the answer.

'ceramics muddling order up' is the wordplay.
I cannot quite see how this works, but
an anagram of 'ceramics' is 'mericasc' which is within the answer.
'up' is within the answer.
A single letter 'a' remains which might be clued in a way I don't see.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Independent.

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