Doctor met it in Verdi compositions (12)
I believe the answer is:
divertimenti
'compositions' is the definition.
(divertimento is a kind of composition)
'doctor met it in verdi' is the wordplay.
'doctor' is an anagram indicator.
'met'+'it'+'in'+'verdi'='metitinverdi'
'metitinverdi' anagrammed gives 'DIVERTIMENTI'.
(Other definitions for divertimenti that I've seen before include "entertaining pieces" , "compositions" .)