The most common and most likely answer to this crossword clue is the 7 letter word STEPPED
I've seen this crossword clue in The Guardian
S
T
E
P
P
E
D
Buddy explains!
The straight part
We know that "Walked/in a series of stages" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case walked/in a series of stages = stepped.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 STEPPED mean?
STEPPED verb- To move the foot in walking; to advance or recede by raising and moving one of the feet to another resting place, or by moving both feet in succession.
- To walk; to go on foot; especially, to walk a little distance.
- To walk slowly, gravely, or resolutely.
- To move mentally; to go in imagination.
- To set, as the foot.
- To fix the foot of (a mast) in its step; to erect.
- Provided with a step or steps; having a series of offsets or parts resembling the steps of stairs.