Gravely serious complaint about music (6)
I believe the answer is:
tragic
'gravely serious' is the definition.
I can't tell whether this defines the answer.
'complaint about music' is the wordplay.
'complaint' becomes 'tic' (a tic is a medical complaint).
'about' indicates putting letters inside.
'music' becomes 'rag' (rag is a kind of music**).
'tic' going around 'rag' is 'TRAGIC'.
Can you help me to learn more?
(Other definitions for tragic that I've seen before include "Heart-rending" , "Grievous" , "Exceedingly sad" , "Terrible" , "Causing extreme distress or sorrow" .)