The most common and most likely answer to this crossword clue is the 9 letter word DANDELION
I've seen this crossword clue in Independent
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More clues leading to the result DANDELION
- Joiner in food store supported by plant
- Dined alone cut off in plant
- One blooming cool-looking cat, I’m told!
- Daughter vetted on-line ad
- Ground in lane with odd weed
- Daniel Defoe wastes the enemy – ‘Fierce beast’ is a weed
- Short book by northern drunk elevated wine variety
- Report of comic hero, one growing wild?
- One unwelcome in bed, periodically displaying clock
- Desperate man, drunk, promoted new kind of wine
Buddy explains!

The straight part
We know that "a weed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a weed = dandelion.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 DANDELION mean?
DANDELION noun- Any of the several species of plant in the genus Taraxacum, characterised by yellow flower heads and notched, broad-ended leaves, especially the common dandelion (Taraxacum officinale).
- The flower head or fruiting head of the dandelion plant.
- A yellow colour, like that of the flower.
- Of a yellow colour, like that of the flower.