Found in Arabian desert and South American mountains (5)
I believe the answer is:
andes
'south american mountains' is the definition.
(I've seen this before)
'found in arabian desert and' is the wordplay.
'found in' indicates the answer is hidden within the clue.
'ANDES' can be found hidden inside 'arabian desert and'.
(Other definitions for andes that I've seen before include "danes found in mountains" , "Danes in S American mountains" , "Mountains of 6 dn" , "A geographical feature" , "The range of llamas?" .)