Some fancy an idea to give poison (7)

I believe the answer is:

cyanide

'poison' is the definition.
(cyanide is poisonous)

'some fancy an idea to' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'CYANIDE' is hidden in the letters of 'fancy an idea to'.

'give' acts as a link.

(Other definitions for cyanide that I've seen before include "Poisonous compound" , "killer" , "Nice day (anag) - poison" , "Extremely poisonous salt" , "Highly toxic substance" .)

I've seen this clue in The Telegraph.

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