Approaching, pull along a road (6)
'approaching' is the definition.
Both the definition and answer are adjectives.
Perhaps they are linked in a way I don't understand?
'pull along a road' is the wordplay.
'pull along' becomes 'tow' (towing is a kind of pulling along).
'road' becomes 'rd' (abbreviation).
Can you help me to learn more?
(Another definition for toward that I've seen is "In the direction of".)