Production of Rheingold cut short, end of northern opera (9)
I believe the answer is:
lohengrin
'opera' is the definition.
(I've seen this before)
'production of rheingold cut short end of northern' is the wordplay.
'production of' indicates anagramming the letters.
'cut short' means to remove the last letter.
'end of' suggests the final letters.
The final letter of 'northern' is 'n'.
'rheingold' with its final letter taken off is 'rheingol'.
'rheingol' with letters rearranged gives 'lohengri'.
'lohengri'+'n'='LOHENGRIN'
(Other definitions for lohengrin that I've seen before include "Wagnerian opera" , "Musical entertainment" , "Wagner opera" .)