Loud perpetual complaint (5)
I believe the answer is:
fever
'complaint' is the definition.
'loud perpetual' is the wordplay.
'loud' becomes 'f' (short for forte - 'loud' in music).
'perpetual' becomes 'ever' (I can't justify this - if you can you should give a lot more credence to this answer).
'f'+'ever'='FEVER'
Can you help me to learn more?
(Other definitions for fever that I've seen before include "eg Malaria" , "General excitement" , "Nervous excitement, high temperature" , "Early part of flu" , "A rise in the temperature from infection" .)