Robert Lindsay? (6)
I believe the answer is:
wagner
'robert lindsay?' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
Can you help me to learn more?
(Other definitions for wagner that I've seen before include "Composer of ''The Flying Dutchman'' etc" , ""The Ring of the Nibelung" composer" , "German operatic composer, d. 1883" , "German composer of The Flying Dutchman" , "German opera composer" .)