"An old roue" is mere banter (8)
I believe the answer is:
badinage
'banter' is the definition.
(badinage is a kind of banter)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for badinage that I've seen before include "Good-natured banter or teasing" , "Beg Diana with good-humoured teasing" , "Ribbing" , "Raillery, give-and-take" , "Frivolous backchat" .)