The most common and most likely answer to this crossword clue is the 10 letter word DEVOTIONAL
I've seen this crossword clue in The Times
D
E
V
O
T
I
O
N
A
L
More clues leading to the result DEVOTIONAL
Buddy explains!

The straight part
We know that "Sacred" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sacred = devotional.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 DEVOTIONAL mean?
DEVOTIONAL noun- A brief religious service.
- A textor piece of music or writing to be used for devotion.
- (usually religious) Of or pertaining to devotion or worship.