The most common and most likely answer to this crossword clue is the 5 letter word KIANG
K
I
A
N
G
More clues leading to the result KIANG
Buddy explains!
The straight part
We know that "ass" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ass = kiang.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 KIANG mean?
KIANG noun- A large wild ass, Equus kiang, native to the Tibetan Plateau.