Pole position (4)
I believe this clue is a double definition.
'pole' is the first definition.
(I've seen this before)
'position' is the second definition.
(post is a kind of position)
(Other definitions for post that I've seen before include "Put a letter in the box - stop it" , "Mail; wooden stake" , "Station" , "Send via the mail" , "Publicly display; send" .)
(Other definitions for arctic that I've seen before include "-- Circle; -- fox" , "Freezing cold like North Pole" , "Cold region in the northern hemisphere" , "Area around the North Pole" , "Poplar region" .)