The most common and most likely answer to this crossword clue is the 5 letter word SLOOP
I've seen this crossword clue in The Times
S
L
O
O
P
More clues leading to the result SLOOP
- Funds raised for boat
- Taking portside tack, a gamble for ship
- Vessel taking supplies west
- Sailing boat needs only small areas of water to turn
- Puddles of water around vessel
- Boat from south on circular course
- Shares making a comeback for single master
- Places to swim found returning to vessel
- Ship — that which you can bet on having capsized
- Boat causes waters to rise
Buddy explains!

The straight part
We know that "Vessel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vessel = sloop.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 SLOOP mean?
SLOOP noun- A single-masted sailboat with only one headsail.
- A sailing warship, smaller than a frigate, with its guns all on one deck.
- A sloop-of-war, smaller than a frigate, larger than a corvette.