The most common and most likely answer to this crossword clue is the 9 letter word TRAMPLING
I've seen this crossword clue in The Daily Telegraph
T
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Buddy explains!
The straight part
We know that "Treading" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case treading = trampling.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 TRAMPLING mean?
TRAMPLING verb- To crush something by walking on it.
- (by extension) To treat someone harshly.
- To walk heavily and destructively.
- (by extension) To cause emotional injury as if by trampling.
- The act of something that tramples.