Expose count to topic (7,6)
I believe the answer is:
subject matter
'topic' is the definition.
(I've seen this before)
'expose count' is the wordplay.
'expose' becomes 'subject' (I can't explain this - if you can you should believe this answer much more).
'count' becomes 'matter' (synonyms).
'subject'+'matter'='SUBJECT-MATTER'
'to' is the link.
Can you help me to learn more?
(Other definitions for subject matter that I've seen before include "The substance under consideration" , "The topic being dealt with" , "Theme" , "Book content" , "citizen feel important" .)