The most common and most likely answer to this crossword clue is the 4 letter word HOBO
I've seen this crossword clue in The Daily Telegraph
H
O
B
O
More clues leading to the result HOBO
- Clownish sort of dingbat
- US broadcaster pinching round bum
- Bum note coming out of hard thing to play
- Down-and-out ex-pupil in house
- Itinerant forgetting piano at end of two dances
- Hospital with type of blood found in 1A bum
- Chap leaves American city to become a drifter
- Vagrant’s Holy Book, half-missing
- Vagrant who needs nothing more than a warm place
- I love a bum
Buddy explains!

The straight part
We know that "Vagrant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vagrant = hobo.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 HOBO mean?
HOBO noun- A wandering homeless person, especially one illegally travelling by rail or a penniless, unemployed bum.
- Any migratory laborer, whether homeless or not.
- A kind of large handbag.
- (perhaps pejorative) To be a hobo, tramp, bum etc.