He was surrealist in modern style (5)
I believe the answer is:
ernst
This clue could be a double definition.
'he' is the first definition.
'surrealist in modern style' is the second definition.
'ernst' can be an answer for 'surrealist' (I've seen this before). I am unsure of the 'in modern style' bit.
'was' is the link.
Can you help me to learn more?
(Other definitions for ernst that I've seen before include "artist's name" , "Max -, twentieth century German Surrealist artist" , "Surrealist; stern (anag.)" , "German-born painter, Max, co-founder of dadaism, d. 1976" , "He painted" .)