Gossiping about milliner -- one no good (10)
I believe the answer is:
chattering
'gossiping' is the definition.
('chatter' can be a synonym of 'gossip')
'about milliner one no good' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'milliner' becomes 'hatter' (synonyms).
'one no good' becomes 'ing' (I am not sure about this - if you are sure you should believe this answer much more).
'c'+'hatter'+'ing'='CHATTERING'
Can you help me to learn more?
(Other definitions for chattering that I've seen before include "babbling" , "Educated people expressing views on the issues of the day" .)