The most common and most likely answer to this crossword clue is the 9 letter word ORATORIES
I've seen this crossword clue in The Sunday Telegraph
O
R
A
T
O
R
I
E
S
Buddy explains!
The straight part
We know that "Chapels" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chapels = oratories.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 ORATORIES mean?
ORATORIES noun- A private chapel or prayer room.
- A large Roman Catholic church.