They work unaided to produce fruit in a fitful sun (10)

I believe the answer is:

automatons

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'they work unaided to' is the definition.
The definition suggests an adverb but the answer is not.

'fruit in a fitful sun' is the wordplay.
'fruit' becomes 'tomato' (type of fruit).
'in' is an insertion indicator.
'fitful sun' becomes 'uns' (I can't justify this - if you can you should believe this answer much more).
'a'+'uns'='auns'
'tomato' placed into 'auns' is 'AUTOMATONS'.

'produce' acts as a link.

Can you help me to learn more?

(Another definition for automatons that I've seen is " They act unthinkingly".)

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

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