Starts off more hazardous for someone on the piste (5)
I believe the answer is:
skier
'someone on the piste' is the definition.
'skier' can be an answer for 'someone' (skier is a kind of someone). I'm not sure about the 'on the piste' bit.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for skier that I've seen before include "He glides across snow for fun" , "Sport exponent" , "sporting figure" , "Mountain racer" , "he's possibly going downhill quickly" .)