Talk about new slogan (5)
I believe the answer is:
chant
'slogan' is the definition.
'talk about new' is the wordplay.
'talk' becomes 'chat' (I've seen this before).
'about' indicates putting letters inside.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'chat' placed around 'n' is 'CHANT'.
(Other definitions for chant that I've seen before include "Mantra" , "Repeated rhythmic song" , "Incantatory song" , "Type of group singing" , "Recite singingly" .)