Victorian work is old anthem entirely unfinished (8)
I believe the answer is:
iolanthe
'victorian' is the definition.
Both the answer and definition are singular nouns.
Perhaps you can see a link between them that I don't see?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for iolanthe that I've seen before include "The Peer and the Peri is its alternative title" , "Staged work" , "G&S piece" , "G&S operetta" , "G&S's eponymous fairy" .)