The most common and most likely answer to this crossword clue is the 8 letter word FOREMAST
I've seen this crossword clue in The Times
F
O
R
E
M
A
S
T
Buddy explains!
The straight part
We know that "There's one on schooner" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case there's one on schooner = foremast.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 FOREMAST mean?
FOREMAST noun- The mast nearest the bow, on a ship with more than one mast.