One divulging secrets in three books about the French queen (7)
I believe the answer is:
blabber
'one divulging secrets' is the definition.
'three books about the french queen' is the wordplay.
'three' becomes 'b' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'books' becomes 'bb'.
'about' is a charade indicator (letters next to each other).
'the french' becomes 'la'.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'bb' put after 'la' is 'labb'.
'b'+'labb'+'er'='BLABBER'
'in' is the link.
(Another definition for blabber that I've seen is " Chatter".)