They go downhill fast in cold weather (6)
I believe the answer is:
skiers
'they go downhill fast' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for skiers that I've seen before include "Persons on the slopes" , "aerial shots" , "Highballs" , "They race on snow" , "They glide on the piste" .)