Taking A-road, head west for treeless plain (6)
I believe the answer is:
tundra
'for treeless plain' is the definition.
(I've seen this in another clue)
'taking a-road head west' is the wordplay.
'taking' becomes 'tun' (I can't justify this - if you can you should give a lot more credence to this answer).
'road' becomes 'rd' (abbreviation).
'head west' shows that the letters should be reversed in order.
'a'+'rd'='ard'
'ard' reversed gives 'dra'.
'tun'+'dra'='TUNDRA'
(Other definitions for tundra that I've seen before include "Vast flat treeless zone" , "northern waste" , "Area of permanently frozen subsoil" , "Treeless frozen Arctic plain" , "Arctic plain with permafrost" .)