South American rave-up in ruins (8)
I believe the answer is:
peruvian
'south american' is the definition.
(someone from Peru)
'rave-up in ruins' is the wordplay.
'ruins' is an anagram indicator.
'rave'+'up'+'in'='raveupin'
'raveupin' anagrammed gives 'PERUVIAN'.
(Other definitions for peruvian that I've seen before include "Of someone from Lima, say" , "Nationality of citizen of Lima" , "Eg, native of Lima" , "Certain South American" , "Paddington's nationality" .)