Crossword Genius

If no oven, concede; should be pre-prepared stuff (11,4)

Ross

I believe the answer is:

convenience food

I'm a little stuck... Click here to teach me more about this clue!

'stuff' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'if no oven concede should be pre-prepared' is the wordplay.
'if no oven concede' can be anagrammed to 'CONVENIENCE FOOD'.
But, I am unsure how this is indicated.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.
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