Six cardinals in Rome meeting a nationalist with no military involvement (8)

I believe the answer is:
civilian
'nationalist with no military involvement' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'six cardinals in rome meeting a' is the wordplay.
I cannot quite see how this works, but
'six' could be 'vi' (Roman numerals) and 'vi' is located in the answer.
'a' could be 'an' and 'an' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for civilian that I've seen before include "One who is not a member of the forces of law and order." , "Nonmilitary person" , "Citizen (non-military)" , "Non-combatant" , "out of service" .)
