John Steinbeck's middle name (5)
I believe the answer is:
ernst
'john steinbeck's middle name' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ernst that I've seen before include "Young partner" , "Max --, German painter" , "German-born painter, Max, co-founder of dadaism, d. 1976" , "Max __; Dadaist" , "He painted" .)