Against coins not using English metal? Sort of (8)
'metal? sort of' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'against coins not using english' is the wordplay.
'against' becomes 'anti' (I've seen this before).
'coins' becomes 'money' (I've seen this before).
'not using' suggests deleting specific letters.
'english' becomes 'E' (abbreviation).
'money' with 'e' removed is 'mony'.
(Other definitions for antimony that I've seen before include "Brittle element", "Semimetallic element", "My nation (anag) - metallic element", "Bluish-white element, symbol Sb", "Toxic metallic element used in semiconductors".)