The most common and most likely answer to this crossword clue is the 5 plus 4 letter word GOOSE STEP
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More clues leading to the result GOOSE STEP
Buddy explains!

The straight part
We know that "March" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case march = goose step.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 GOOSE STEP mean?
GOOSE STEP noun- A style of marching in which the feet are lifted high in the air in front.
- To march with a goose-step.