Confidently bold slogan at heart of your primary set of beliefs (8)
I believe the answer is:
ideology
'set of beliefs' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for ideology that I've seen before include "Body of ideas" , "Body of beliefs" , "Ideas forming basis of political theory" , "System of beliefs" , "Creed" .)