Erté's genre (3,4)
I believe the answer is:
art deco
'erte's genre' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for art deco that I've seen before include "Style of 1920s/30s" , "1920s and 1930s ornamental style" , "Old style" , "Style popular in the 1920s and '30s" , "Architecture and design movement of the 1920s and 30s" .)