Works of Sartre (3)
I believe the answer is:
art
'works' is the definition.
(I've seen this before)
'of sartre' is the wordplay.
'of' indicates a hidden word.
'ART' is hidden in the letters of 'sartre'.
(Other definitions for art that I've seen before include "Expertise" , "For example, Blakey's creative" , "Works of creative imagination" , "Drawing" , "-- Garfunkel, singer" .)