The most common and most likely answer to this crossword clue is the 6 letter word ASHRAM
I've seen this crossword clue in The Guardian
A
S
H
R
A
M
More clues leading to the result ASHRAM
- A quiet river in the morning as a place of retreat
- Like husband with memory going into retreat
- A fake king’s in retreat
- Resistance met in a bogus retreat in India
- Marsha rebuilt Hindu retreat
- Like hotel stuff in place of seclusion
- Rupees found in a fake holy man’s retreat
- A king’s taken in by charlatan’s religious retreat
- Retreat a pretence to cover first of raids
- England’s fifth king stopping imposter’s retreat
Buddy explains!

The straight part
We know that "religious retreat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case religious retreat = ashram.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 ASHRAM mean?
ASHRAM noun- A secluded religious hermitage inhabited by gurus, or the population of such a hermitage.