Possible Clues:

• Arranger composing for a singer (not female)
• Arranger of scores in a group making comeback
• Runner who's old unexpectedly regains lead in race
• Came up with arrangements for Bach, for instance, a stingy type needing no introduction
• Manager of revolutionary region as source of rumours
• Runner regains form to chase gold
• Manager's journal is here at the centre
• One responsible for arranging rare song, I suspect
• Co-ordinator ordered garrison to arrest enemy's No. 1
• Fixer of musical instrument is getting particular note right