The most common and most likely answer to this crossword clue is the 7 letter word SAILORS
I've seen this crossword clue in The Daily Telegraph
S
A
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L
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Buddy explains!
The straight part
We know that "Mariners" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mariners = sailors.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 SAILORS mean?
SAILORS noun- A person in the business of navigating ships or other vessels
- Someone knowledgeable in the practical management of ships.
- A member of the crew of a vessel; a mariner; a common seaman.
- A person who sails sailing boats as a sport or recreation.
- Any of various nymphalid butterflies of the genera Neptis, Pseudoneptis and Phaedyma, having white markings on a dark base and commonly flying by gliding.