Section of alp is terrific ski run (5)
I believe the answer is:
piste
'ski run' is the definition.
(I've seen this before)
'section of alp is terrific' is the wordplay.
'section of' indicates the answer is hidden within the clue.
'PISTE' can be found hidden inside 'alp is terrific'.
(Other definitions for piste that I've seen before include "Ski track" , "slippery slope" , "Ski trail" , "Skiing trail" , "A ski run of compacted snow" .)