The most common and most likely answer to this crossword clue is the 5 letter word FADED
I've seen this crossword clue in The Guardian
F
A
D
E
D
More clues leading to the result FADED
Buddy explains!

The straight part
We know that "disappeared" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case disappeared = faded.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 FADED mean?
FADED verb- To grow weak; to lose strength; to decay; to perish gradually; to wither, as a plant.
- To lose freshness, color, or brightness; to become faint in hue or tint; hence, to be wanting in color.
- To sink away; to disappear gradually; to grow dim; to vanish.
- To cause to fade.
- To bet against.
- (sometimes figurative) That has lost some of its former colour or intensity.
- High on drugs; stoned