Exaggerated first opera and final word about an Italian composer (7)
I believe the answer is:
overdid
'exaggerated' is the definition.
('overdo' can be a synonym of 'exaggerate')
'first opera and final word about an italian composer' is the wordplay.
'first opera' becomes 'o' (vst letter of 'opera').
'and' says to put letters next to each other.
'final' says to take the final letters.
'about' is a charade indicator (letters next to each other).
'an italian composer' becomes 'verdi' (I've seen this before).
The final letter of 'word' is 'd'.
'd' after 'verdi' is 'verdid'.
'o'+'verdid' is 'OVERDID'.
(Other definitions for overdid that I've seen before include "Exaggerated" , "Made too much of" , "operated excessively" , "went too far" .)