Discovery of ski run, good, at last (4)
I believe the answer is:
find
'discovery' is the definition.
(synonyms)
'of ski run good at last' is the wordplay.
'at last' says to take the final letters.
The last letters of 'of ski run good' are 'FIND'.
(Other definitions for find that I've seen before include "Encounter, locate" , "Come across" , "Discover by chance" , "Locate or discover" , "Track down" .)