Part of Nabucco Verdi definitely exaggerated (7)
I believe the answer is:
overdid
'exaggerated' is the definition.
('overdo' can be a synonym of 'exaggerate')
'part of nabucco verdi definitely' is the wordplay.
'part of' says the answer is hidden in the clue.
'OVERDID' can be found hidden inside 'nabucco verdi definitely'.
(Other definitions for overdid that I've seen before include "Made too much of" , "Exaggerated" , "went too far" , "operated excessively" .)