Cher's music, fancy stuff entertaining posh society (8)
I believe the answer is:
populace
'society' is the definition.
(thesaurus)
'cher's music fancy stuff entertaining posh' is the wordplay.
'cher's music' becomes 'pop' (pop music).
'fancy stuff' becomes 'lace' (fancy material).
'entertaining' indicates putting letters inside (inviting in, as for dinner).
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-U).
'pop'+'lace'='poplace'
'poplace' placed around 'u' is 'POPULACE'.
(Other definitions for populace that I've seen before include "Residents" , "Citizens" , "The plebs" , "Inhabitants" , "Common people" .)