The most common and most likely answer to this crossword clue is the 6 letter word ARCANA
I've seen this crossword clue in The Times
A
R
C
A
N
A
More clues leading to the result ARCANA
- A sample of polar Canada's secrets
- Secrets of a famous wedding venue penetrated by Rector
- A headless whale keeping a number of secrets
- Secret remedies college fed to a prince
- Mysteries revealed in Five Go Off In A Caravan novel
- In war, can accept things being kept secret
- Mysteries a rainbow’s genesis is able to answer?
- A right place for the miraculous mysteries
- Only part of the circle gets the stories and secrets
- A church has articles on mysteries
Buddy explains!

The straight part
We know that "secrets" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case secrets = arcana.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 ARCANA mean?
ARCANA noun- Specialized knowledge that is mysterious to the uninitiated.
- A mystery or deep secret.
- An elixir or secret remedy.