Surrealist in modern studio (5)
I believe the answer is:
ernst
'surrealist' is the definition.
(I've seen this before)
'in modern studio' is the wordplay.
'in' indicates a hidden word.
'ERNST' is hidden in the letters of 'modern studio'.
(Other definitions for ernst that I've seen before include "Max __; Dadaist" , "He painted" , "Max --, German painter" , "Surrealist; stern (anag.)" , "Young partner" .)