The most common and most likely answer to this crossword clue is the 4 letter word SOOK
S
O
O
K
More clues leading to the result SOOK
Buddy explains!

The straight part
We know that "Aussie wimp" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case aussie wimp = sook.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 SOOK mean?
SOOK verb- To use the mouth and lips to pull in (a liquid, especially milk from the breast).
- To perform such an action; to feed from a breast or teat.
- To put the mouth or lips to (a breast, a mother etc.) to draw in milk.
- To extract, draw in (a substance) from or out of something.
- To work the lips and tongue on (an object) to extract moisture or nourishment; to absorb (something) in the mouth.
- To pull (something) in a given direction, especially without direct contact.
- To perform fellatio.
- To be inferior or objectionable: a general term of disparagement, sometimes used with at to indicate a particular area of deficiency.
- Familiar name for a calf.
- Familiar name for a cow.
- A cow or sheep.
- A poddy calf.
- A call for calves.
- A call for cattle.
- A call for cattle or sheep.
- A crybaby, a complainer, a whinger; a shy or timid person, a wimp; a coward.
- A sulk or complaint; an act of sulking.
- A street market, particularly in Arabic- and Somali-speaking countries; a place where people buy and sell goods.
- A mature female Chesapeake Bay blue crab, Callinectes sapidus.