Repeated piece of music before service, loud for masses (4-4)
I believe the answer is:
riff-raff
'repeated piece' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'music before service loud for masses' is the wordplay.
I cannot really understand how this works, but
'music' could be 'riff' (riff is a kind of music) and 'riff' is located in the answer.
'service' could be 'raf' (Royal Air Force) and 'raf' is found in the answer.
'loud' could be 'f' (short for forte - 'loud' in music) and 'f' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for riff-raff that I've seen before include "Rabble" , "rubbish" , "Hoi polloi" , "Disreputable people" , "Undesirables" .)