The most common and most likely answer to this crossword clue is the 10 letter word OBSERVANCE
I've seen this crossword clue in The Times
O
B
S
E
R
V
A
N
C
E
More clues leading to the result OBSERVANCE
Buddy explains!
The straight part
We know that "ritual" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ritual = observance.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 OBSERVANCE mean?
OBSERVANCE noun- The practice of complying with a law, custom, command or rule.
- The custom of celebrating a holiday or similar occasion.
- Observation or the act of watching.
- A rule governing a religious order, especially in the Roman Catholic church.
- That which is to be observed.
- Reverence; homage.