A prose rendering of musical dramas
I believe the answer is:
operas
'musical dramas' is the definition.
(I've seen this in another clue)
'a prose rendering' is the wordplay.
'rendering' indicates anagramming the letters.
'a'+'prose'='aprose'
'aprose' with letters rearranged gives 'OPERAS'.
'of' acts as a link.
(Other definitions for operas that I've seen before include "Plays in which the words are sung" , "Nabucco and Tosca" , "Dramatic musicals in which words are sung" , "They're written by 1 across" , "Musical plays" .)