Brass, say, for military leader and others (5)
I believe the answer is:
metal
'brass say' is the definition.
(I know that brass is a type of copper-base alloy)
'military leader and others' is the wordplay.
'leader' says to take the initial letters.
'and others' becomes 'etal' (short for 'et alia', 'and others' in Latin).
The first letter of 'military' is 'm'.
'm'+'etal'='METAL'
'for' is the link.
(Other definitions for metal that I've seen before include "Copper, perhaps" , "Aluminium or copper for instance" , "tin, perhaps" , "Iron, gold or silver, for example" , "Maybe copper" .)