Loud Australian wearing dresses for expeditions (7)
I believe the answer is:
safaris
'for expeditions' is the definition.
(safari is a kind of expedition)
'loud australian wearing dresses' is the wordplay.
'loud' becomes 'f' (short for forte - 'loud' in music).
'australian' becomes 'A' (common abbreviation).
'wearing' is an insertion indicator.
'dresses' becomes 'saris' (sari is a kind of dress).
'f'+'a'='fa'
'fa' put into 'saris' is 'SAFARIS'.
(Other definitions for safaris that I've seen before include "African trips" , "Expeditions" .)