Italian baroque composer (7)
'italian baroque composer' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for corelli that I've seen before include "Arcangelo --, Italian baroque composer" , "Arcangelo, seventeenth to eighteenth century Italian composer, violinist" , "Marie - - , romantic 17" , "Captain -'s Mandolin (de Bernires)" , "A mandolin-playing Captain" .)
(Other definitions for vivaldi that I've seen before include "Italian composer of 'The Four Seasons'" , "Italian composer known as "the red priest"" , "Italian composer (the Red Priest) , d.1741" , "Italian composer, Antonio (d. 1741)" , "Venetian composer ("The Red Priest"), d. 1741" .)