Endless parties entertaining street performer (7)
I believe the answer is:
artiste
'performer' is the definition.
(an artiste is a performer or entertainer)
'endless parties entertaining street' is the wordplay.
'endless' indicates the central letters.
'entertaining' is an insertion indicator (inviting in, as for dinner).
'street' becomes 'st' (abbreviation).
The middle of 'parties' is 'artie'.
'artie' enclosing 'st' is 'ARTISTE'.
(Other definitions for artiste that I've seen before include "A sitter for creative person" , "Trouper" , "Professional performer" , "Player" , "Theatre performer" .)