Crossword Genius

Bet on songs being out-of-date (4,7)

Ross

I believe the answer is:

back numbers

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'bet' is the definition.
I know nothing about this answer so I can't tell whether this works.

'on songs being out-of-date' is the wordplay.
'on' means one lot of letters go next to another.
'songs' becomes 'numbers' (as in musical numbers).
'being out-of-date' becomes 'back' ('back' can be a synonym of 'out-of-date').
'numbers' after 'back' is 'BACK NUMBERS'.

Can you help me to learn more?

(Other definitions for back numbers that I've seen before include "old hat!" , "Epidurals" .)

I've seen this clue in The Globe and Mail.
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