Which chemical makes fast fruit? (9)

I believe the answer is:

quicklime

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

'which chemical' is the definition.
I can't tell whether this definition defines the answer.

'fast fruit?' is the wordplay.
'fast' becomes 'quick' (similar in meaning).
'fruit?' becomes 'lime' (lime is a kind of fruit).
'quick'+'lime'='QUICKLIME'

'makes' acts as a link.

Can you help me to learn more?

(Other definitions for quicklime that I've seen before include "Calcium oxide" , "Field dressing to reduce acidity" .)

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

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