The most common and most likely answer to this crossword clue is the 5 letter word CREWS
I've seen this crossword clue in Financial Times
C
R
E
W
S
Buddy explains!

The straight part
We know that "Groups of sailors" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case groups of sailors = crews.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 CREWS mean?
CREWS noun- A pen for livestock such as chickens or pigs
- The Manx shearwater.