The most common and most likely answer to this crossword clue is the 6 letter word NUDISM
I've seen this crossword clue in The Daily Telegraph
N
U
D
I
S
M
More clues leading to the result NUDISM
- Daughter is coming in nearly frozen — having tried this?
- Copper's collected by miners revealing practice
- Disappointing D minus gets serious dressing down
- Rolling around in mud’s a revealing practice
- Greek character, female, writing about having nothing on
- Peelers’ practice of immersing the underworld in biblical content, briefly
- There are colonies where this practice is barely appropriate
- New German car’s failing to start on motorway being out of gear
- Girl’s entering into union with a preference for no clothes!
- A barely established philosophy?
Buddy explains!

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.