First course in expressionist art, erotic! (7)
I believe the answer is:
starter
'first course' is the definition.
(first course in a meal)
'in expressionist art erotic' is the wordplay.
'in' indicates a hidden word.
'STARTER' is hidden in the letters of 'expressionist art erotic'.
(Other definitions for starter that I've seen before include "Beginner, or opening course of meal" , "Type of home" , "First course of meal" , "No substitute" , "One giving signal to begin race" .)