The most common and most likely answer to this crossword clue is the 9 letter word GARDENING
I've seen this crossword clue in Financial Times
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Buddy explains!
The straight part
We know that "working on a plot" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case working on a plot = gardening.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 GARDENING mean?
GARDENING verb- To grow plants in a garden; to create or maintain a garden.
- Of a batsman, to inspect and tap the pitch lightly with the bat so as to smooth out small rough patches and irregularities.
- The process or action of cultivating the soil, particularly in a garden; the care of a garden; horticulture.
- The act of a batsman prodding at the pitch with his bat, typically in order to flatten any bumps