Quarrel - it turns very loud (4)
I believe the answer is:
tiff
'quarrel' is the definition.
(informal term for an argument)
'it turns very loud' is the wordplay.
'turns' is a reversal indicator.
'very loud' becomes 'ff' (musical abbreviation).
'it' backwards is 'ti'.
'ti'+'ff'='TIFF'
(Other definitions for tiff that I've seen before include "Petty squabble" , "Quarrel (colloq.)" , "dispute" , "pet" , "Slight argument" .)