Clue: Continue to show a certain undergarment, a German number (3,2,3,1,6)
Answer: AIR ON THE G STRING
Explanation: Definition: a German number
A charade of AIR ON ('continue to show') plus THE G-STRING ('a certain undergarment'); the *Air* from Johann Sebastian Bach's *Orchestral Suite No. 3* was arranged by August Willhelmj (another German), transposing the first violin part of the original so that it may be played entirely on the lowest string of the violin, the G-string.