A prose version of musical dramas (6)
I believe the answer is:
operas
'musical dramas' is the definition.
(I've seen this before)
'a prose version' is the wordplay.
'version' is an anagram indicator.
'a'+'prose'='aprose'
'aprose' with letters rearranged gives 'OPERAS'.
'of' acts as a link.
(Other definitions for operas that I've seen before include "O spare these dramas" , "Cos? fan tutte and The Magic Flute" , "Plays in which the words are sung" , "Musical dramas" , "Musical plays" .)