Loud organ gets a little frightening (8)
I believe the answer is:
fearsome
'frightening' is the definition.
('fearsome' can be a synonym of 'frightening')
'loud organ gets a little' is the wordplay.
'loud' becomes 'f' (A musical term).
'organ' becomes 'ear' (ear is a kind of organ).
'gets' says to put letters next to each other.
'a little' becomes 'some' (I've seen this before**).
'f'+'ear'+'some'='FEARSOME'
(Other definitions for fearsome that I've seen before include "Fame rose and became frightening" , "Horrendous" , "Awful" , "Daunting" , "Formidable" .)