Welsh muso John about to get on the beer (4)

I believe the answer is:

cale

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'welsh muso john' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'about to get on the beer' is the wordplay.
'about' becomes 'c' (circa).
'to get on' is a charade indicator (letters next to each other) (in a down clue, some letters go above others).
'the beer' becomes 'ale' (type of beer).
'c'+'ale'='CALE'

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I've seen this clue in The Independent.

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