The most common and most likely answer to this crossword clue is the 6 letter word LIEDER
I've seen this crossword clue in The Guardian
L
I
E
D
E
R
More clues leading to the result LIEDER
- One taking part in the French and German songs
- Story provided by the Schubertian songs
- Art-songs remain greatly loved, bar the third
- Songs principal first violinist talked of
- Numbers of Germans were dishonest on retreats
- We hear No 1 songs
- Songs the chief heard
- The French claimed independence with the German song
- Songs the Führer sang?
- Story to introduce the foreign songs
Buddy explains!

The straight part
We know that "Songs the Führer sang?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case songs the führer sang? = lieder.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does LIEDER mean?
LIEDER noun- An art song, sung in German and accompanied on the piano.