One declining to follow vehicle — preferred one to go on foot (6,7)

'one to go on foot' is the definition.
(footwear)

'one declining to follow vehicle preferred' is the wordplay.
'one declining' becomes 'slipper' (slip can mean to decline or fall).
'to follow' means one lot of letters go next to another (some letters go after or follow others).
'vehicle' becomes 'car' (car is a kind of vehicle).
'preferred' becomes 'pet' (synonyms).
'car'+'pet'='carpet'
'slipper' after 'carpet' is 'CARPET-SLIPPER'.