Longest continental mountain range
I believe the answer is:
andes
'longest continental mountain range' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for andes that I've seen before include "Aconcagua the highest in this range" , "World's longest mountain range" , "Mountain range in South America" , "Mountains of 6 dn" , "South American mountain chain" .)