One refuses military service, like eternally peaceful saint (8)
I believe the answer is:
pacifist
'saint' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for pacifist that I've seen before include "Anti-war person, believes in peaceful settlements" , "One is opposed to violence as a means of settling disputes" , "One refusing military service" , "Peacemaker" , "One abhorring violence" .)