Entertainer is treat when sozzled (7)
I believe the answer is:
artiste
'entertainer' is the definition.
(artiste is a kind of entertainer)
'is treat when sozzled' is the wordplay.
'when sozzled' indicates an anagram (sozzled can mean drunk).
'is'+'treat'='istreat'
'istreat' anagrammed gives 'ARTISTE'.
(Other definitions for artiste that I've seen before include "Attires (anag.)" , "Professional performer" , "'Public performer, dancer or singer (7)'" , "Performers" , "Theatre performer" .)