Possible Clues:

• One who pens numbers
• Boy (half German) accepts summons to be a musician
• Dance partner is a bookmaker who does his work in bars perhaps?
• One jotting down a few notes?
• Dance partner is a bookmaker who does his work in bars?
• Resorting to change around West Berlin, for example
• Knows a thing or two about air quality developing suitable lines on the right track
• Porter, perhaps, bending strong wire
• Composer, say, of Winterreise (or Winter's Journeying holds good)
• Pop music composer