Fine, delicate wind instrument in black box (6,8)
I believe the answer is:
flight recorder
'black box' is the definition.
(I've seen this in another clue)
'fine delicate wind instrument in' is the wordplay.
'fine' becomes 'f' (abbreviation).
'delicate' becomes 'light' (similar in meaning).
'wind instrument in' becomes 'recorder' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'f'+'light'+'recorder'='FLIGHT RECORDER'
Can you help me to learn more?
(Other definitions for flight recorder that I've seen before include "black box" , "may help to determine cause of accident" , "One revealing cause of crash" .)