The most common and most likely answer to this crossword clue is the 7 letter word CREWMAN
I've seen this crossword clue in The Guardian
C
R
E
W
M
A
N
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 = crewman.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 CREWMAN mean?
CREWMAN noun- A member of a crew, especially the crew of a ship.
- Synonym of armoured crewman