The most common and most likely answer to this crossword clue is the 5 letter word NASTY
I've seen this crossword clue in The Daily Telegraph
N
A
S
T
Y
More clues leading to the result NASTY
- Finally clean a pig enclosure that's unpleasant!
- Unpleasant refusal to accommodate street
- A street in New York is unpleasant
- Mean and ill-considered, taking note instead initially
- A street in New York is very unpleasant
- Very unpleasant royal line suffers double beheading
- Negative word about good person is unpleasant
- Refusal to accept good man is bad
- Stay drunk with knight becoming aggressive
- Mean no holy man to enter
Buddy explains!

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 NASTY mean?
NASTY noun- Something nasty.
- (preceded by "the") Sexual intercourse.
- A video nasty.
- Dirty, filthy.
- Contemptible, unpleasant (of a person).
- Objectionable, unpleasant (of a thing); repellent, offensive.
- Indecent or offensive; obscene, lewd.
- Spiteful, unkind.
- Awkward, difficult to navigate; dangerous.
- Grave or dangerous (of an accident, illness etc.).
- Formidable, terrific; wicked.