Country girl one spies in Spanish region (7)
I believe the answer is:
galicia
'country' is the definition.
(I know that Galicia is a country)
'girl one spies in spanish region' is the wordplay.
'girl' becomes 'gal'.
'one' becomes 'i' (Roman numeral).
'spies in spanish region' becomes 'cia' (I can't explain this - if you can you should believe this answer much more).
'gal'+'i'+'cia'='GALICIA'
Can you help me to learn more?
(Other definitions for galicia that I've seen before include "part of Spain" , "Autonomous region of Spain" , "North-western region of Spain" , "Region of NW Spain" .)