Artist's material for sculpting picked up (4)
I believe the answer is:
klee
'artist's' is the definition.
(painter Paul Klee, 1879-1940)
'material for sculpting picked up' is the wordplay.
'material for sculpting' becomes 'clay' (a sculptor may use clay).
'picked up' shows a homophone (sound like).
'clay' sounds like 'KLEE'.
(Other definitions for klee that I've seen before include "Auction offerer" , "Paul ---, Swiss artist" , "Paul --, Swiss surrealist" , "Paul - - , Swiss painter" .)