Sing in the Alps (5)
I believe the answer is:
yodel
'sing in the alps' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for yodel that I've seen before include "Warbling voice" , "Vocalise" , "Sing in high pitch like Swiss mountain dwellers" , "Sing partially falsetto" , "Sing in Tyrolean fashion" .)