The most common and most likely answer to this crossword clue is the 7 letter word TANTRIC
I've seen this crossword clue in The Guardian
T
A
N
T
R
I
C
More clues leading to the result TANTRIC
- Type of sex requiring whip and 80 per cent skill
- Like some mysticism spread in tract
- … in tract that’s circulating, referencing Buddhist works
- Worker in a jiffy endlessly recalling Buddhist ritual?
- Of 21 philosophy carried by a distant rickshaw
- Religious writing‘s bit of magic not totally engaging worker
- Religious writing’s disseminated in tract
- Seaman in command safeguarding holy books of religious writings
- Religious writing’s important richness not wholly apparent
- Beat deception, ignoring the end of scriptures
Buddy explains!

The straight part
We know that "Of 21 philosophy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case of 21 philosophy = tantric.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 TANTRIC mean?
TANTRIC adjective- Describing Vajrayana Buddhism.
- Describing any of several branches of yoga or esoteric traditions rooted in India.