Vehicle used in winter has extremely special advantage (6)
I believe the answer is:
sledge
'vehicle' is the definition.
(sledge is a kind of vehicle)
'extremely special advantage' is the wordplay.
'extremely' suggests removing the centre (only the extremes of the word are used).
'advantage' becomes 'edge' (having the edge is having an advantage).
'special' with its centre taken out is 'sl'.
'sl'+'edge'='SLEDGE'
'used in winter has' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for sledge that I've seen before include "heavy tool" , "Large heavy hammer" , "Vehicle mounted on runners" , "Make offensive remarks" , "Vehicle for travelling over snow" .)