Concoction lethal for some -- e.g. cider I'm brewing (9)

I believe the answer is:

germicide

I'm a little stuck... Click here to teach me more about this clue!

'concoction lethal for' is the definition.
I can't tell whether this defines the answer.

'e g cider i'm brewing' is the wordplay.
'brewing' is an anagram indicator.
'e'+'g'+'cider'+'im'='egciderim'
'egciderim' anagrammed gives 'GERMICIDE'.

'some' is the link.

Can you help me to learn more?

(Other definitions for germicide that I've seen before include "Disinfectant" , "Agent that destroys disease-carrying microorganisms" , "antiseptic" , "Substance destroying harmful microorganisms" .)

I've seen this clue in The Independent.

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