Quiet morning; representative brought back spoil! (6)
I believe the answer is:
pamper
'spoil' is the definition.
(I know that spoil can be written as pamper)
'quiet morning representative brought back' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'morning' becomes 'am' (as in 12:00 AM).
'representative' becomes 'rep' (rep is a kind of representative).
'brought back' says the letters should be written in reverse.
'rep' back-to-front is 'per'.
'p'+'am'+'per'='PAMPER'
(Other definitions for pamper that I've seen before include "'Indulge, spoil (6)'" , "Treat with excessive indulgence" , "Spoil, over-indulge" , "Treat with over-indulgence" , "Mollycoddle" .)