Composer showing heart before bad turns (7)
I believe the answer is:
corelli
'composer' is the definition.
(Arcangelo Corelli)
'heart before bad turns' is the wordplay.
'heart' becomes 'core' ('core' can be a synonym of 'heart').
'before' says to put letters next to each other.
'bad' becomes 'ill' ('ill' can be similar in meaning to 'bad').
'turns' says the letters should be written in reverse.
'ill' reversed gives 'lli'.
'core'+'lli'='CORELLI'
'showing' is the link.
(Other definitions for corelli that I've seen before include "Arcangelo, seventeenth to eighteenth century Italian composer, violinist" , "Captain -'s Mandolin (de Bernires)" , "A mandolin-playing Captain" , "Marie - - , romantic 17" , "Arcangelo --, Italian baroque composer" .)