Toboggan leads off slalom lying edgewise downhill (4)
I believe the answer is:
sled
'toboggan' is the definition.
(toboggan is a type of sled)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for sled that I've seen before include "Vehicle on runners" , "Sledge" , "Toboggan (mainly US)" , "Winter transport" , "Snow vehicle" .)