The most common and most likely answer to this crossword clue is the 3 plus 3 letter word FAG END
I've seen this crossword clue in The Guardian
F
A
G
E
N
D
More clues leading to the result FAG END
- Very last bit of information — there's enthusiasm to collect it
- Rage for seizing lowdown butt
- Remnant lawman found in ward
- Fellow with short list of things to be done with a stub
- Butt of a gendarme’s covered
- 24 across following detailed schedule
- Work hard to complete a butt
- Fine list of items missing the last bit — the bit that doesn’t matter
- What’s left after following schedule is cut short?
- What’s left after fine programme is cut short?
Buddy explains!

The straight part
We know that "stub" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stub = fag end.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 END mean?
FAG END noun- Last remnant
- Frayed end of a length of cloth or rope
- The unsmoked end of a cigarette or cigar