The most common and most likely answer to this crossword clue is the 6 letter word MARROW
I've seen this crossword clue in The Daily Telegraph
M
A
R
R
O
W
More clues leading to the result MARROW
- Eat mostly in the morning, knocking back veg
- Vegetable is to spoil, grown without its outer parts
- Substance found in mass on Dart
- Last part of anagram indicator
- Vegetable essence
- Male pointer finds tasty bit of bone
- Last part of anagram indicator in essence
- Spoil argument for vegetable
- Heart monitor’s first indicator
- Vegetable to spoil one of the lines in garden?
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 = marrow.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 MARROW mean?
MARROW noun- The substance inside bones which produces blood cells.
- A kind of vegetable like a large courgette/zucchini or squash.
- The pith of certain plants.
- The essence; the best part.
- The inner meaning or purpose.
- Bone marrow biopsy.
- Semen.
- A friend, pal, buddy, mate.
- One of a pair; a match; a companion; an intimate associate.