Poisonous to several, I see (5)

I believe the answer is:

toxic

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'poisonous' is the definition.
(similar in meaning)

'to several i see' is the wordplay.
'several i' becomes 'xi' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'see' becomes 'C' (the word for the letter, according to Chambers).
'to'+'xi'+'c'='TOXIC'

Can you help me to learn more?

(Other definitions for toxic that I've seen before include "word describing bad things" , "Harmful - cox it (anag)" , "Poisonous, noxious" , "Deadly - venomous" .)

I've seen this clue in the Evening Standard.

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