The most common and most likely answer to this crossword clue is the 4 letter word DOH!
I've seen this crossword clue in Independent
D
O
H
!
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 DOH! mean?
DOH! interjection- Expresses frustration or anger, especially at one’s own stupidity.
- An anglicised spelling of do. A syllable used in solfège to represent the first and eighth tonic of a major scale.