The most common and most likely answer to this crossword clue is the 3 letter word BAM
I've seen this crossword clue in Independent
B
A
M
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 BAM mean?
BAM interjection- Representing a loud noise or heavy impact.
- Representing a sudden or abrupt occurrence.
- A ned; a bampot.
- An imposition; a cheat; a hoax.
- To impose on (someone) by a falsehood; to cheat.
- To jeer or make fun of.
- Abbreviation of bare-arse minimum.