The most common and most likely answer to this crossword clue is the 5 letter word ASTER
I've seen this crossword clue in Financial Times
A
S
T
E
R
More clues leading to the result ASTER
- Flower festival failing to open
- Flower festival not opening
- Wife leaving layabout, one often found in bed?
- Late bloomer, briefly behind
- Flower maiden abandoned by ruler
- Daisy’s teacher docking marks
- Waste recycling protects flower
- Reduced to tears, as festival fails to start
- Bloomer by man in charge first off
- Daisy needs a bit taken off behind
Buddy explains!

The straight part
We know that "flower" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case flower = aster.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 ASTER mean?
ASTER noun- Any of several plants of the genus Aster; one of its flowers.
- A star-shaped structure formed during the mitosis of a cell.
- A star.