The most common and most likely answer to this crossword clue is the 5 letter word BREVE
B
R
E
V
E
More clues leading to the result BREVE
- Mark's first wife overlooked by brother
- Note always a note, when written up!
- Part of speech backed up English note
- Note British Romeo brought to First Lady
- Bishop always upset item in bar
- Note how cleric fills empty bottle
- Accent at all British, in retrospect?
- Note black Republican brought to First Lady
- Note reverberations echoing a bit
- Note – always a particular one echoing
Buddy explains!

The straight part
We know that "long note" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case long note = breve.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 BREVE mean?
BREVE noun- A semicircular diacritical mark (˘) placed above a vowel, commonly used to mark its quantity as short.
- A double whole note.
- Any writ or precept under seal, issued out of any court.
- The great ant thrush of Sumatra (Pitta gigas), which has a very short tail.