Playboy model -- not a woman but ... (3-5-4)
I believe the answer is:
man-about-town
'playboy' is the definition.
(synonyms)
'model not a woman but' is the wordplay.
'model' is an anagram indicator.
'not'+'a'+'woman'+'but'='notawomanbut'
'notawomanbut' with letters rearranged gives 'MAN-ABOUT-TOWN'.
(Other definitions for man-about-town that I've seen before include "He's fashionable and sophisticated" , "Sophisticated socialite" .)