"In the Hall of the Mountain King" composer (5)
I believe the answer is:
grieg
'in the hall of the mountain king composer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for grieg that I've seen before include "Scandinavian composer, d. 1907" , "Composer of incidental music to Peer Gynt, d.1907" , "Edvard ---, composer" , "Norwegian composer (Peer Gynt)" , "Composer of the incidental music for Ibsen's Peer Gynt" .)