Ancient Andeans in the money endlessly (5)
I believe the answer is:
incas
'ancient andeans' is the definition.
(I've seen this in another clue)
'in the money endlessly' is the wordplay.
'the money' becomes 'cash' (cash is a type of money).
'endlessly' means to remove the last letter.
'cash' with its final letter removed is 'cas'.
'in'+'cas'='INCAS'
(Other definitions for incas that I've seen before include "conquered by Spain" , "South Americans whose empire fell to Spain" , "Members of ancient Peruvian race" , "Old Peruvians" , "People from Andes who settled in Peru" .)