Interpret tune discovered by classical composer (7)
I believe the answer is:
unravel
'interpret' is the definition.
(thesaurus)
'tune discovered by classical composer' is the wordplay.
'discovered' indicates the central letters.
'by' means one lot of letters go next to another.
'classical composer' becomes 'ravel' (Maurice Ravel).
The central letters of 'tune' are 'un'.
'un'+'ravel'='UNRAVEL'
(Other definitions for unravel that I've seen before include "Come undone; solve" , "Make sense of" , "Become undone" , "Solve the problem" , "Disentangle knitted wool or solve mystery" .)