The most common and most likely answer to this crossword clue is the 7 letter word HOLIEST
I've seen this crossword clue in The Guardian
H
O
L
I
E
S
T
More clues leading to the result HOLIEST
- Most divine fiction given coverage in Mass
- Most pious but also most flawed, perhaps
- Most religious stories occurred in sweltering environment
- Most religious stories are found in hotel bible section
- Working the soil is most sacrosanct
- Most venerated entertainer concealing deceit
- Like the most sacred thing that is penned by composer
Buddy explains!

The straight part
We know that "Most pious/most flawed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case most pious/most flawed = holiest.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 HOLIEST mean?
HOLIEST adjective- Having, or being full of, holes
- Dedicated to a religious purpose or a god.
- Revered in a religion.
- Morally perfect or flawless, or nearly so.
- Separated or set apart from (something unto something or someone else).
- Set apart or dedicated for a specific purpose, or for use by a single entity or person.
- Used as an intensifier in various interjections.