Excitedly telling niece news (12)
I believe the answer is:
intelligence
'news' is the definition.
(intelligence can mean news or information)
'excitedly telling niece' is the wordplay.
'excitedly' indicates anagramming the letters (letters excited or stimulated into a new form).
'telling'+'niece'='tellingniece'
'tellingniece' anagrammed gives 'INTELLIGENCE'.
(Other definitions for intelligence that I've seen before include "Brains -- news" , "Covert information" , "Spy reports" , "Dope" , "Mind; news" .)