Opposed to bread lacking key element (8)

I believe the answer is:

antimony

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'lacking key element' is the definition.
'antimony' can be an answer for 'element' (antimony is a kind of element). I am not sure about the 'lacking key' bit.

'opposed to bread' is the wordplay.
'opposed to' becomes 'anti' (anti means opposing something).
'bread' becomes 'mony' (I can't justify this - if you can you should believe this answer much more).
'anti'+'mony'='ANTIMONY'

Can you help me to learn more?

(Other definitions for antimony that I've seen before include "My nation (anag) - metallic element" , "Toxic metallic element used in semiconductors" , "Semimetallic element" , "One element" , "Bluish-white element, symbol Sb" .)

I've seen this clue in The Times.

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