McCartney, say, is a singer first (7)

I believe the answer is:

bassist

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'mccartney' is the definition.
(Paul McCartney is a bassist)

'singer first' is the wordplay.
'singer' becomes 'bass' (bass is a kind of singer).
'first' becomes 'ist' (ist resembles 1st).
'bass'+'ist'='BASSIST'

'say is a' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for bassist that I've seen before include "Musician" , "jazz player" .)

I've seen this clue in The Daily Express.

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