Mark entertains in a talk that's playful (8)
I believe the answer is:
badinage
'talk that's playful' is the definition.
'mark entertains in a' is the wordplay.
'mark' becomes 'badge' (badging is a kind of marking).
'entertains' indicates putting letters inside.
'in'+'a'='ina'
'badge' going around 'ina' is 'BADINAGE'.
(Other definitions for badinage that I've seen before include "Amiable banter" , "Wordplay" , "Drollery" , "Ribbing" , "Frivolous repartee" .)