CIA deny mixing poison (7)

I believe the answer is:

cyanide

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

'cia deny mixing' is the wordplay.
'mixing' is an anagram indicator.
'cia'+'deny'='ciadeny'
'ciadeny' anagrammed gives 'CYANIDE'.

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

I've seen this clue in The Sun.

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