He composed line put in exam papers for sending back (7)
I believe the answer is:
vivaldi
'he composed' is the definition.
(composer Antonio Vivaldi)
'line put in exam papers for sending back' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'put in' means one lot of letters goes inside another.
'exam' becomes 'viva' (short for 'viva voce', an oral examination).
'papers for' becomes 'id' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sending back' shows that the letters should be reversed in order.
'id' reversed gives 'di'.
'viva'+'di'='vivadi'
'l' placed into 'vivadi' is 'VIVALDI'.
Can you help me to learn more?
(Other definitions for vivaldi that I've seen before include "Italian composer of 'The Four Seasons'" , "Italian composer, Antonio (d. 1741)" , "Italian composer known as "the red priest"" , "Venetian composer ("The Red Priest"), d. 1741" , "Italian composer (the Red Priest) , d.1741" .)