Compete in a slalom (3)
I believe the answer is:
ski
'compete in a slalom' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ski that I've seen before include "Glide or race across snow with feet attachments" , "What one might do in Alps" , "Use runners crossing snow" , "runner in winter" , "Travel across snow" .)