National theme (7)
I believe the answer is:
subject
I believe this is a double definition.
'national' is the first definition.
('subject' can be a synonym of 'national')
'theme' is the second definition.
('subject' can be a synonym of 'theme')
(Other definitions for subject that I've seen before include "Citizenship' at school maybe" , "Expose; field of study" , "Subordinate - part of sentence" , "Put down" , "Topic - branch of study - citizen" .)