The most common and most likely answer to this crossword clue is the 7 letter word TROOPED
T
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O
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Buddy explains!
The straight part
We know that "Marched" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case marched = trooped.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 TROOPED mean?
TROOPED verb- To move in numbers; to come or gather in crowds or troops.
- To march on; to go forward in haste.
- To move or march as if in a crowd.