National issue (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')
'issue' is the second definition.
(I've seen this before)
(Other definitions for subject that I've seen before include "School topic" , "Branch of knowledge" , "Musical theme" , "Topic being discussed" , "topic of conversation?" .)