Songs the kaiser heard? (6)
I believe the answer is:
lieder
'songs' is the definition.
(lied is a kind of song)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for lieder that I've seen before include "numbers in German" , "works by Schubert" , "Relied on German song genre" , "songs from Berlin?" , "Musical settings for solo voice and piano" .)