Runner on snow finally approaches Karakoram mountain (3)
I believe the answer is:
ski
'runner on snow' is the definition.
(I've seen this in another clue)
'finally approaches karakoram mountain' is the wordplay.
'finally' indicates one should take the final letters.
'karakoram mountain' becomes 'ki' (I can't justify this - if you can you should believe this answer much more).
The final letter of 'approaches' is 's'.
's'+'ki'='SKI'
Can you help me to learn more?
(Other definitions for ski that I've seen before include "Sliding runner" , "Alpine runner" , "Winter sport item" , "Slide downhill, sportingly" , "run on 26 [SNOW]" .)