The most common and most likely answer to this crossword clue is the 8 letter word CABOTAGE
I've seen this crossword clue in The Guardian
C
A
B
O
T
A
G
E
Buddy explains!

The straight part
We know that "Naval right" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case naval right = cabotage.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 CABOTAGE mean?
CABOTAGE noun- The transport of goods or passengers between two points in the same country.
- The right to engage in such transport.
- The exclusive right of a country to control such transport.