Maybe one isn't a countryman (8)
I believe the answer is:
estonian
'countryman' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'maybe one isn't a' is the wordplay.
'maybe' indicates anagramming the letters.
'one'+'isnt'+'a'='oneisnta'
'oneisnta' with letters rearranged gives 'ESTONIAN'.
Can you help me to learn more?
(Other definitions for estonian that I've seen before include "Eg, native of Tallinn" , "Baltic state native" , "Eastern Europe" , "Northern European" , "Native of Tallinn, say" .)