Kind to yield immediately? Not sure! (1,4,4)

I believe the answer is:

i dont know

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'not sure' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'kind to yield immediately?' is the wordplay.
'yield' is an anagram indicator (I've seen 'yielding' mean this).
'immediately?' becomes 'now' (I've seen this before).
'kind'+'to'='kindto'
'kindto' with letters rearranged gives 'idontk'.
'idontk'+'now'='I DONT KNOW'

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I've seen this clue in The Guardian.

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