Sing "The Lonely Goatherd," say (5)
I believe the answer is:
yodel
'sing the lonely goatherd say' 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 "Sing in high trilling tone like Swiss mountaineer" , "Sing using falsetto" , "Sing partly falsetto" , "Sing like some Tyroleans" , "Sing warblingly" .)