Witty banter (8)
I believe the answer is:
repartee
'witty banter' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for repartee that I've seen before include "Witty exchange" , "Banter - pear tree (anag)" , "Quick and witty conversation" , "Witty comments" , "Ready wit" .)