Stop living in Australia or I'm off! (5)
I believe the answer is:
adieu
'i'm off' is the definition.
I can't tell whether this definition defines the answer.
'stop living in australia' is the wordplay.
'stop living' becomes 'die' (I've seen this before).
'in' indicates putting letters inside.
'australia' becomes 'au'.
'die' put inside 'au' is 'ADIEU'.
'or' is the link.
Can you help me to learn more?
(Other definitions for adieu that I've seen before include "Au revoir (to a kind friend?)" , "Leave" , "Farewell to France" , "Fare thee well!" , "Some say it when leaving" .)