Drives up taking primarily tarmacked roads (7)
I believe the answer is:
streets
'roads' is the definition.
(I know this)
'drives up taking primarily tarmacked' is the wordplay.
'drives' becomes 'steers' (I've seen this in another clue).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'taking' means one lot of letters goes inside another.
'primarily' says to take the initial letters.
The first letter of 'tarmacked' is 't'.
'steers' in reverse letter order is 'sreets'.
'sreets' placed around 't' is 'STREETS'.
(Other definitions for streets that I've seen before include "Built-up roads" , "City thoroughfares" , "significantly ahead?" , "Ways" , "Avenues" .)