The most common and most likely answer to this crossword clue is the 4 letter word SINS
I've seen this crossword clue in The Guardian
S
I
N
S
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 SINS mean?
SINS noun- A violation of God's will or religious law.
- A misdeed.
- A sin offering; a sacrifice for sin.
- An embodiment of sin; a very wicked person.
- A flaw.
- To commit a sin.
- A letter of the Hebrew alphabet; שׂ
- A letter of the Arabic alphabet; س
- A traditional tube skirt worn by Lao and Thai women, particularly northern Thai and northeastern Thai women.