The most common and most likely answer to this crossword clue is the 5 letter word TANSY
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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 = tansy.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 TANSY mean?
TANSY noun- A herbaceous plant with yellow flowers, of the genus Tanacetum, especially Tanacetum vulgare.
- A dish common in the seventeenth century, made of eggs, sugar, rose water, cream, and the juice of herbs (including tansy), baked with butter in a shallow dish. "Originally flavoured with tansy, but by Pepys's time generally having spinach as its predominant flavouring."