The most common and most likely answer to this crossword clue is the 8 letter word FEVERFEW
I've seen this crossword clue in The Times
F
E
V
E
R
F
E
W
More clues leading to the result FEVERFEW
- Passion not many displayed for European plant
- Plant some after a hot spell
- High temperature that’s exhausting, did you say, for plant?
- There’s always hardly any after fine plant
- Plant in front of florist’s always thin on the ground
- By virtue of high temperature, hardly any greenery
- . Daisy's family member, female, always a handful
- Perennial plant not many associated with disease
Buddy explains!

The straight part
We know that "European plant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case european plant = feverfew.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 FEVERFEW mean?
FEVERFEW noun- A European aromatic perennial herb, Tanacetum parthenium (or Chrysanthemum parthenium or Pyrethrum parthenium), having daisy-like flowers; valued as a traditional medicine, especially for headaches.