Crossword Genius

In a European country, he may be in grey (3)

Ross

I believe the answer is:

man

I'm a little stuck... Click here to teach me more about this clue!

'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" .)

I've seen this clue in the Evening Standard.
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