The most common and most likely answer to this crossword clue is the 3 letter word FAG
I've seen this crossword clue in The Daily Telegraph
F
A
G
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 FAG mean?
FAG noun- In textile inspections, a rough or coarse defect in the woven fabric.
- (dated in US and Canada) A cigarette.
- The worst part or end of a thing.
- A chore: an arduous and tiresome task.
- A younger student acting as a servant for senior students.
- (used mainly in passive form) To make exhausted, tired out.
- To droop; to tire.
- For a younger student to act as a servant for senior students in many British boarding schools.
- To have (a younger student) act as a servant in this way.
- To work hard, especially on menial chores.
- (usually offensive, sometimes affectionate) A homosexual man, especially (usually derogatory) an especially effeminate or unusual one.
- An annoying person.