Language of south India (5)
I believe the answer is:
hindi
'language' is the definition.
(Hindi is an example)
'of south india' is the wordplay.
'of' indicates a hidden word.
'HINDI' is hidden within 'south india'.
(Other definitions for hindi that I've seen before include "An official language of India" , "tongue" , "One of India's official languages" , "Ind. Language" , "Indian language" .)