The most common and most likely answer to this crossword clue is the 6 letter word ESSENE
I've seen this crossword clue in The Guardian
E
S
S
E
N
E
More clues leading to the result ESSENE
- From German city, European ascetic type
- Member of ascetic fraternity in reduced numbers, forsaking extremes
- Somewhat boundless energy for an ascetic
- Old ascetic Jewish sect member – some finesse needed
- Old Jewish sect lessened without its extreme elements
- Untouchable turned on eastern ascetic
- Ancient Jew from German city quarter
- Religious sect having hearts of blessed oneness
- A being about to leave Jewish sect
- Ascetic’s actual existence, one not getting old
Buddy explains!

The straight part
We know that "ascetic/ascetic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ascetic/ascetic = essene.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.