The most common and most likely answer to this crossword clue is the 10 letter word WINDJAMMER
W
I
N
D
J
A
M
M
E
R
More clues leading to the result WINDJAMMER
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 = windjammer.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 WINDJAMMER mean?
WINDJAMMER noun- One who plays a wind instrument, especially a bugler in the army.
- A sailing ship; especially a large, iron-hulled, square-rigged ship with three or more masts.
- A member of the crew of a ship of this kind.
- A windbag, a loquacious person.
- A weatherproof jacket (windcheater).