The most common and most likely answer to this crossword clue is the 6 letter word LARGOS
I've seen this crossword clue in The Guardian
L
A
R
G
O
S
More clues leading to the result LARGOS
Buddy explains!

The straight part
We know that "Passages" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case passages = largos.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 LARGOS mean?
LARGOS noun- A very slow tempo
- A musical piece or movement in such a tempo