In a European country, he may be in grey (3)
I believe the answer is:
man
'european country he may be in grey' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'in a' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found within the answer.
A single letter 'm' remains 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 man that I've seen before include "Valet" , "The most destructive and polluting animal" , "knight, perhaps?" , "Irish Sea isle" , "Soldier" .)