Aussie native king banished from castle? (3)
I believe the answer is:
roo
'aussie native' is the definition.
(I've seen this in other clues)
'king banished from castle?' is the wordplay.
'king' becomes 'k'.
'banished from' is a deletion indicator.
'castle?' becomes 'rook' ('rook' can be a synonym of 'castle').
'rook' with 'k' removed is 'ROO'.
(Other definitions for roo that I've seen before include "bounder" , "large animal" , "Kanga's son (Pooh)" , "Marsupial (abbrev.)" , "Marsupial (informal)" .)