Serviceman finds one in metal alloy (7)
I believe the answer is:
soldier
This clue could be a double definition.
'serviceman' is the first definition.
(soldier is a kind of serviceman)
'one in metal alloy' is the second definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'finds' acts as a link.
Can you help me to learn more?
(Other definitions for soldier that I've seen before include "Member of the military" , "regular?" , "Eg, private" , "Military person" , "One enlisted" .)