The most common and most likely answer to this crossword clue is the 10 letter word STARBOARDS
I've seen this crossword clue in The Guardian
S
T
A
R
B
O
A
R
D
S
Buddy explains!
The straight part
We know that "Rights" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rights = starboards.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 STARBOARDS mean?
STARBOARDS noun- The righthand side of a ship, boat or aircraft when facing the front, or fore or bow. Used to unambiguously refer to directions according to the sides of the vessel, rather than those of a crew member or object.
- One of the two traditional watches aboard a ship standing a watch in two.