Laudable composition expunged both lines of music (6)
I believe the answer is:
aubade
'music' is the definition.
(I know that aubade is a type of song)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for aubade that I've seen before include "Festive occasion" , "Dawn music or poem" , "Sunrise song" , "Dawn poem, song" , "piece of early music" .)