Rudolf —, painter born in 1854 whose works include The Meal, The Metal Workers and Reading the Koran (5)
I believe the answer is:
ernst
(Other definitions for ernst that I've seen before include "Young partner" , "German-born painter, Max, co-founder of dadaism, d. 1976" , "Max -, twentieth century German Surrealist artist" , "Max --, German painter" , "artist's name" .)