The most common and most likely answer to this crossword clue is the 6 letter word BITCHY
I've seen this crossword clue in Financial Times
B
I
T
C
H
Y
More clues leading to the result BITCHY
- Malicious bachelor causing irritation
- Bishop getting uncomfortable becomes spiteful
- Like a cat, black and suffering from fleas?
- Malicious heartless boy, long imprisoned
- Bishop’s restless and vindictive
- Nasty irritation, according to nurses
- Uncharitable characterisation of a female setter?
- By introducing it, church is vindictive
- a Malicious desire to cut through
Buddy explains!

The straight part
We know that "Nasty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nasty = bitchy.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 BITCHY mean?
BITCHY adjective- Spiteful or malevolent; catty; malicious; unpleasant.
- Irritable.