False witness in Australia rearrested (4)
I believe the answer is:
liar
'false witness' is the definition.
(I've seen this in another clue)
'in australia rearrested' is the wordplay.
'in' says the answer is hidden in the clue.
'LIAR' is hidden within 'australia rearrested'.
(Other definitions for liar that I've seen before include "one telling a story" , "Perjuror" , "Phoney" , "not straight [one]" , "Fibber" .)