First character left union note about uranium, a metal (9)
I believe the answer is:
aluminium
'metal' is the definition.
(I know that aluminium is a type of metal)
'first character left union note about uranium a' is the wordplay.
I cannot really see how this works, but
'first' could be 'i' (I in Roman numerals eg Elizabeth I) and 'i' is located in the answer.
'character' could be 'u' and 'u' is found within the answer.
'left' could be 'al' (I've seen this in other clues) and 'al' is found in the answer.
'union' could be 'u' (common abbreviation as in 'Trades Union Congress') and 'u' is present in the answer.
'note' could be 'n' (abbreviation) and 'n' is found within the answer.
The remaining letters 'mim' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for aluminium that I've seen before include "Metallic element found in bauxite" , "Lightweight metal" , "Al" , "Silvery metallic element" , "Light metal" .)