The most common and most likely answer to this crossword clue is the 10 letter word SEMIT(ON)E
I've seen this crossword clue in The Guardian
S
E
M
I
T
(
O
N
)
E
Buddy explains!

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 SEMIT(ON)E mean?
SEMIT(ON)E noun- The musical interval equal (exactly or approximately) to half a tone or one-twelfth of an octave
- Any of the pitches of the chromatic scale