It was once the talk of India (8)
I believe the answer is:
sanskrit
'talk of india' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?
'it was once the' is the wordplay.
I cannot quite understand how this works, but
'it' could be 'sa' (old-fashioned abbreviation for sex appeal) and 'sa' is found in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sanskrit that I've seen before include "Ancient Indian language" , "Ancient official language of India" , "Ancient Indo-European language" , "Ancient Hindu tongue" , "Ancient language of Hindus in India" .)