The most common and most likely answer to this crossword clue is the 10 letter word SEPULCHRAL
I've seen this crossword clue in Financial Times
S
E
P
U
L
C
H
R
A
L
More clues leading to the result SEPULCHRAL
Buddy explains!
The straight part
We know that "melancholy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case melancholy = sepulchral.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 SEPULCHRAL mean?
SEPULCHRAL adjective- Relating to a grave or to death; funereal.
- Suggestive of a grave or of death; having a hollow and deep sound.