The most common and most likely answer to this crossword clue is the 6 letter word ROSARY
I've seen this crossword clue in The Times
R
O
S
A
R
Y
More clues leading to the result ROSARY
- Succeeded in shouting a string of requests etc
- Parks maybe outside of Romney as a sign of devotion
- Certain prayers are unfinished in optimistic environment
- Promising to hold retreat, initially after a series of prayers
- A sorry ragged string of beads
- Sorry criminal steals archbishop’s first beads
- Herb wanting space in flower bed
- Sorry, a criminal makes up prayers
- Sorry, failing to keep a Catholic devotion
- Errors fairly regularly found in prayers
Buddy explains!

The straight part
We know that "sign of devotion" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sign of devotion = rosary.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 ROSARY mean?
ROSARY noun- Prayer beads, a string of beads used to keep track of repetitions in prayer, particularly in the Roman Catholic Marian prayer "Hail Mary" (Ave Maria)
- A Roman Catholic devotion involving the repetition of a series of Marian prayers, usually 5, 15, or 20 decades of "Hail Marys", each decade beginning with "Our Father" and ending with "Glory Be to the Father", but sometimes including other Roman Catholic, Anglican, or Lutheran prayers.
- (by extension) A series or collection of thoughts, literary pieces, etc. intended for similar contemplation.
- A 13th-century coin minted in Europe as a counterfeit debased form of the sterling silver penny of Edward I, at first accepted as a halfpenny and then outlawed.
- A rose garden.