The most common and most likely answer to this crossword clue is the 5 letter word CATTY
I've seen this crossword clue in The Daily Telegraph
C
A
T
T
Y
More clues leading to the result CATTY
- Spiteful getting claws out, perhaps?
- Malicious person sticking to soft drinks in bar
- Bitchy? Yes and no
- Bike races in island surroundings, like the Manx?
- Chinese measure seen to be spiteful
- Backbiting eccentric has leader downgraded
- Ill-natured like Mrs Norris?
- Absent-minded? Scratch the head and become spiteful
- Talkative with hour spent backbiting
Buddy explains!

The straight part
We know that "backbiting" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case backbiting = catty.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 CATTY mean?
CATTY adjective- (of a person or remark) With subtle hostility in an effort to hurt, annoy or upset, particularly among women.
- Resembling or characteristic of a cat.
- A (unit of) weight used in China, generally standardized as half a kilogram.