The Sound of Music makes an excessive demand (6)
I believe the answer is:
strain
This clue could be a double definition.
'the sound of music' is the first definition.
(strain can mean a piece of music)
'an excessive demand' is the second definition.
'strain' can be an answer for 'demand' (thesaurus). I'm unsure of the 'an excessive' bit.
'makes' is the link.
Can you help me to learn more?
(Other definitions for strain that I've seen before include "Muscle injury - tension" , "Exert oneself to the utmost" , "Overtired" , "Drain off" , "Force - melody" .)