The most common and most likely answer to this crossword clue is the 8 letter word VEGANISM
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result VEGANISM
Buddy explains!
The straight part
We know that "Dietary practice" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dietary practice = veganism.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 VEGANISM mean?
VEGANISM noun- Strict vegetarianism; the practice of eating neither meat nor other animal products, such as fish, milk and milk products, eggs, and honey.
- A way of life which strictly avoids use of any kind of animal products and services that are based on exploitation of living animals.
- A belief that is against the killing of animals for meat consumption; the antithesis to carnism.