Turn new flute composition out for musical (7)
I believe the answer is:
tuneful
'for musical' is the definition.
(I've seen this before)
'turn new flute composition' is the wordplay.
'turn' becomes 'U' (a 'U-turn' is a kind of turn).
'new' becomes 'n' (abbreviation as in New Testament NT).
'composition' is an anagram indicator (letters arranged or composed in a different order).
'u'+'n'+'flute'='unflute'
'unflute' with letters rearranged gives 'TUNEFUL'.
'out' acts as a link.
(Other definitions for tuneful that I've seen before include "Euphonic" , "Melodious" , "Harmonious" , "With a pleasing musical sound" , "Euphonious" .)