Loud and just awful (9)
I believe the answer is:
frightful
'awful' is the definition.
(I've seen this before)
'loud and just' is the wordplay.
'loud' becomes 'f' (short for forte - 'loud' in music).
'and' is a charade indicator (letters next to each other).
'just' becomes 'rightful' (similar in meaning).
'f'+'rightful'='FRIGHTFUL'
(Other definitions for frightful that I've seen before include "savage" , "alarm" , "nasty" , "ugly" , "Appalling" .)