The most common and most likely answer to this crossword clue is the 5 letter word VEGAN
I've seen this crossword clue in The Daily Telegraph
V
E
G
A
N
More clues leading to the result VEGAN
- Picky eater’s vehicle containing 50% eggs
- One won't want milk, say, being kept in vehicle
- Promoter of diet, say, in the forefront
- Star name, one adopting fashionable diet
- Star name following a particular diet
- Woman rejecting animal products, say, found in vehicle
- Strict sort of diet for one in the lead
- One refusing to accept meat in transit, say?
- Careful eater, new age views primarily turning up
- Particular eater of Dutch sandwiches for example
Buddy explains!

The straight part
We know that "Type of diet" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case type of diet = vegan.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 VEGAN mean?
VEGAN noun- A person who does not eat, drink or otherwise consume any animal products
- A person committed to avoiding products and practices that inherently involve animal use, including all foods containing animal products, and to abstaining from direct and intentional harm to animals as far as possible; an adherent to veganism.
- (of a product or practice, especially food) Not containing animal products (meat, eggs, milk, leather, etc) or inherently involving animal use.
- (of a person) Committed to avoiding any product or practice that inherently involves animal use.
- Relating to vegans or veganism.