Part of YSL (4)
'part of ysl' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yves that I've seen before include "Frenchman, so-called?" , "__ Saint Laurent, couturier, d. 2008" , "-- Montand (French actor)" , "French man" , "Montand, Fr. actor" .)
(Another definition for laurent that I've seen is " Yves Saint ... (fashion designer)".)