Parking vehicle first, go for long walk (5)
I believe the answer is:
tramp
'for long walk' is the definition.
(I've seen this before)
'parking vehicle first' is the wordplay.
'parking' becomes 'p' (abbreviation on road signs).
'vehicle' becomes 'tram' (tram is a kind of vehicle).
'first' is a charade indicator (letters next to each other).
'p' put after 'tram' is 'TRAMP'.
'go' is the link.
(Other definitions for tramp that I've seen before include "Footslog" , "Vagrant, drifter" , "Walk heavily or wearily" , "Traveller" , "Walk heavily, as when weary, or through mud" .)