Words or text of an opera (8)
I believe the answer is:
libretto
I believe this clue is a double definition.
'words' is the first definition.
(I've seen this before)
'text of an opera' is the second definition.
(I've seen this in another clue)
(Other definitions for libretto that I've seen before include "Words set to music, especially opera" , "Script for a musical drama" , "component of opera" , "Text set to music in opera" , "11 down book" .)