The most common and most likely answer to this crossword clue is the 3 plus 6 letter word RED ENSIGN
I've seen this crossword clue in The Guardian
R
E
D
E
N
S
I
G
N
More clues leading to the result RED ENSIGN
- Update includes name for flag
- Flag: change motif, perhaps incorporating name
- Complete makeover incorporating new naval flag
- Engineers plan involving new 1A
- Communist officer seen on a merchant ship
- Standard newspaper’s first to come into fashion again
- Flag from onset of nervousness during make-over?
- New designer employed as standard
- Standard elevation ultimately in further plan
- Make a fresh plan covering new standard at sea
Buddy explains!
The straight part
We know that "seen waving on a British vessel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case seen waving on a british vessel = red ensign.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.