Something to eat that's sweet and sour (3,4)

I believe the answer is:

jam tart

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'something to eat' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'sweet and sour' is the wordplay.
'sweet' becomes 'jam' (jam is a kind of sweet).
'and' means one lot of letters go next to another.
'sour' becomes 'tart' (similar in meaning).
'jam'+'tart'='JAM TART'

'that's' is the link.

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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