The most common and most likely answer to this crossword clue is the 7 letter word CHUNDER
I've seen this crossword clue in The Guardian
C
H
U
N
D
E
R
More clues leading to the result CHUNDER
Buddy explains!
The straight part
We know that "Sick in Australia" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sick in australia = chunder.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CHUNDER mean?
CHUNDER noun- Vomit.
- An act of vomiting.
- Heavy, sticky snow that makes snowsports difficult.
- To throw up, to vomit.
- Of a motor vehicle: to rumble loudly, to roar.