Ten operas translated into universal language (9)
I believe the answer is:
esperanto
'universal language' is the definition.
(I've seen this before)
'ten operas translated' is the wordplay.
'translated' indicates anagramming the letters.
'ten'+'operas'='tenoperas'
'tenoperas' with letters rearranged gives 'ESPERANTO'.
'into' acts as a link.
(Other definitions for esperanto that I've seen before include "in which many could communicate?" , "Dr Zamenhof's language" , "composite language" , "words, set up artificially?" , "largely unknown language" .)