The most common and most likely answer to this crossword clue is the 6 letter word STRODE
I've seen this crossword clue in The Sunday Telegraph
S
T
R
O
D
E
More clues leading to the result STRODE
- Marched — and walked in step periodically
- Plodded into the Home Counties and moved on apace
- Walked through wild Dorset
- Walked out with half the street writing verse
- Busy editors, ignoring Independent, walked purposefully
- Marched or walked in two directions
- Galumphed and trampled in midst of Japanese garden
- Walked and travelled by speedboat on vacation
- Good man was up and walked
- Dorset eccentric took steps
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 = strode.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 STRODE mean?
STRODE verb- To walk with long steps.
- To stand with the legs wide apart; to straddle.
- To pass over at a step; to step over.
- To straddle; to bestride.