The most common and most likely answer to this crossword clue is the 9 letter word BUTTERCUP
I've seen this crossword clue in The Times
B
U
T
T
E
R
C
U
P
More clues leading to the result BUTTERCUP
- Flower spread, a hundred having risen
- Flower - bottom part raised, we hear?
- Bachelor, thorough, gets trophy for plant
- Goat, perhaps, caught up in meadow plant
- Plant originally cultivated in flatter surroundings?
- Flower spread gets trophy
- Bloomer spread with cheese and pickle tops posh filling
- Flower putting scent, say, into soft soap
- Plant in bar picked up, having received pure cold water?
- Insect’s fifth to penetrate flatter flower
Buddy explains!

The straight part
We know that "Plant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case plant = buttercup.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 BUTTERCUP mean?
BUTTERCUP noun- Any of many herbs, of the genus Ranunculus, having yellow flowers; the crowfoot.
- Any flower of the genus Narcissus; a daffodil.
- Affectionate or ironic term of address.