Crossword Genius

Son gets upset belly with fruit when it’s past its best? (4,2,4)

Ross

I believe the answer is:

sell-by date

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'it's past its best?' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'son gets upset belly with fruit' is the wordplay.
'son' becomes 's'.
'gets upset' indicates anagramming the letters (I've seen 'getting upset' mean this).
'with' means one lot of letters go next to another.
'fruit' becomes 'date' (date is a kind of fruit).
'belly' anagrammed gives 'ellby'.
's'+'ellby'+'date'='SELL-BY-DATE'

'when' is the link.

Can you help me to learn more?

(Other definitions for sell-by date that I've seen before include "Mark on a perishable" , "Perishable deadline" , "Food shop marking" .)

I've seen this clue in The Times.
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