Alpine falsetto (5)
I believe the answer is:
yodel
'alpine falsetto' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yodel that I've seen before include "Sing in high trilling tone like Swiss mountaineer" , "Alpine mountain call" , "make an off-peak call" , "Sing by alternating between normal voice and falsetto" , "Sing (Swiss style)" .)