The most common and most likely answer to this crossword clue is the 9 letter word HERBALIST
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result HERBALIST
- Medical supplier, graduate, included in that woman’s itinerary
- Plant collector finding her way around island
- Botanical expert with itemised qualifications of female scholar?
- One needing time, it’s said, for a cure?
- Ah! Blister is treated with the remedy he offered
- Healer of that woman near Island Street
- Should one mix basil with the last of coriander?
- Collect short book on very famous plant expert
Buddy explains!

The straight part
We know that "plant expert" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case plant expert = herbalist.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 HERBALIST mean?
HERBALIST noun- A person who treats diseases by means of medicinal herbs.