The most common and most likely answer to this crossword clue is the 9 letter word PRIVATEER
I've seen this crossword clue in The Daily Telegraph
P
R
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V
A
T
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R
More clues leading to the result PRIVATEER
- Pirate very shortly at sea in armed vessel
- Penny had a meal on board river vessel
- Craft needing personal attention, you understand?
- . Prince not quite competing with King after support for filibuster, once
- Sailor and soldier meeting head of state
- Pirate very briefly in action?
- I pervert a sailing vessel
- Picaroon: very short pirate in the making
- Duke, say, catches competitor after docking before time in vessel
- Fellow maintaining essential bit of wiring on container ship
Buddy explains!

The straight part
We know that "Sailor" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sailor = privateer.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 PRIVATEER mean?
PRIVATEER noun- A privately owned warship that had official sanction to attack enemy ships and take possession of their cargo.
- An officer or any other member of the crew of such a ship.
- An advocate or beneficiary of privatization of a government service or activity.
- A private individual entrant into a race or competition who does not have the backing of a large, professional team.
- To function under official sanction permitting attacks on enemy shipping and seizing ship and cargo; to engage in government-sponsored piracy.
- To advocate or benefit from privatization of government services.