Setting for "Heidi" (4)
I believe the answer is:
alps
'setting for heidi' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for alps that I've seen before include "European mountain range" , "Pals put on the mountains" , "Mountain system in south-central Europe" , "Swiss mountains" , "Eur. mountain range" .)