Stop and see changes on journey in March (5-4)

'march' is the definition.
(goose step is a kind of march)

'stop and see changes on journey' is the wordplay.
'and' says to put letters next to each other.
'changes' indicates an anagram.
'on' means one lot of letters go next to another.
'journey' becomes 'go' (journey means to go or travel).
'stop' put after 'see' is 'seestop'.
'seestop' anagrammed gives 'osestep'.
'osestep' after 'go' is 'GOOSE-STEP'.

'in' acts as a link.