The most common and most likely answer to this crossword clue is the 8 letter word KOHLRABI
I've seen this crossword clue in The Times
K
O
H
L
R
A
B
I
More clues leading to the result KOHLRABI
- I abhor kale, regularly used as vegetable
- Short bloke with hair styled something like a cabbage
- . Enhancement for viewers almost crazy to get odd vegetable
- Two chancellors at one
- Plant to get fossil fuel reportedly? Not entirely raving mad
- Vegetable with potassium? Cooks boil hard leaves off end
- Former German chancellor meets disheartened Jewish leader for a sort of 4d
- Chancellor and priest reduced by bishop to vegetables
- Old chancellor and Jewish teacher deprived of a British vegetable
- Chancellor and Prime Minister once limited vegetable
Buddy explains!

The straight part
We know that "vegetable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vegetable = kohlrabi.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 KOHLRABI mean?
KOHLRABI noun- Brassica oleracea var. gongylodes, a variety of the cabbage, having a turnip-shaped edible stem.