The most common and most likely answer to this crossword clue is the 5 letter word SKIFF
I've seen this crossword clue in The Times
S
K
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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 = skiff.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 SKIFF mean?
SKIFF noun- Term used in tea gardens and denotes the act of cutting/pruning the bushes as per the specific norms. Various types of skiff are used viz Light Skiff (LS), Medium Skiff (MS), Deep Skiff (DS) and Level Of Skiff (LOS).
- A small flat-bottomed open boat with a pointed bow and square stern.
- Any of various types of boats small enough for sailing or rowing by one person.
- A light wind/rain/snow, etc.
- To navigate in a skiff.
- To cut (a tea bush) to maintain the plucking table
- (Nova Scotia) a deep blanket of snow covering the ground