Surrealist in modern style (5)
I believe the answer is:
ernst
'surrealist' is the definition.
(I've seen this before)
'in modern style' is the wordplay.
'in' says the answer is hidden in the clue.
'ERNST' is hidden within 'modern style'.
(Other definitions for ernst that I've seen before include "Surrealist; stern (anag.)" , "Max -, twentieth century German Surrealist artist" , "German-born painter, Max, co-founder of dadaism, d. 1976" , "He painted" , "Young partner" .)