Mountains in the Libyan Desert (5)
I believe the answer is:
andes
'mountains' is the definition.
(I've seen this before)
'in the libyan desert' is the wordplay.
'in' says the answer is hidden in the clue.
'ANDES' is hidden within 'libyan desert'.
(Other definitions for andes that I've seen before include "A geographical feature" , "Mountain range in South America" , "danes found in mountains" , "South American mountains" , "Peak District" .)