Work out the age of bubbly when daughter moves west (6-4)

I believe the answer is:

carbon-date

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'work out the age of bubbly' is the definition.
I know nothing about this answer so I can't tell whether this works.

'when daughter moves west' is the wordplay.
I cannot really understand how this works, but
'when' could be 'on' (I've seen this in other clues) and 'on' is located in the answer.
'daughter' could be 'd' (genealogical abbreviation) and 'd' is found within the answer.
This explanation may well be incorrect...

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