Wild party for Australian, after a fashion (10)
I believe the answer is:
saturnalia
'wild party' is the definition.
(I've seen this before)
'australian after a fashion' is the wordplay.
'after a fashion' indicates anagramming the letters (letters re-fashioned).
'australian' anagrammed gives 'SATURNALIA'.
'for' acts as a link.
(Other definitions for saturnalia that I've seen before include "revels" , "Wild Roman festival" , "Ancient Roman December festival" , "Old festival" , "wild party" .)