Parking on border of grass (4)
I believe the answer is:
hemp
'grass' is the definition.
(thesaurus)
'parking on border' is the wordplay.
'parking' becomes 'p'.
'on' is a charade indicator (letters next to each other).
'border' becomes 'hem' (I've seen this before).
'p' after 'hem' is 'HEMP'.
'of' is the link.
(Other definitions for hemp that I've seen before include "Rope-making fibre" , "Plant for rope or pot" , "Cannabis sativa" , "Source of drug" , "Grass" .)