Academic, with books advanced, murmured constantly (7)
I believe the answer is:
babbled
'murmured constantly' is the definition.
The definition and answer can be both to do with communicating as well as being past participle verbs.
Maybe you can see an association between them that I can't see?
'academic with books advanced' is the wordplay.
'academic' becomes 'ba'.
'with' is a charade indicator (letters next to each other).
'books' becomes 'BB' (two abbreviations for book).
'advanced' becomes 'led' (I can't explain this - if you can you should believe this answer much more).
'ba'+'bb'+'led'='BABBLED'
Can you help me to learn more?
(Another definition for babbled that I've seen is " (Child) chattered; (stream) murmured".)