A seventh rather flat sporting representative going on record (4,4)

I believe the answer is:

blue note

'a seventh rather flat' is the definition.
(type of musical note)

'sporting representative going on record' is the wordplay.
'sporting representative' becomes 'blue' (sportsperson representing Oxford or Cambridge).
'going on' is a charade indicator (letters next to each other).
'record' becomes 'note' (note is a kind of record).
'blue'+'note'='BLUE NOTE'

I've seen this clue in The Guardian.

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