Possible Clues:

• Prelude; advance
• Obvious regret, dropping resistance to second proposal
• An introduction to something more substantial from visible old city on top of enclave
• Rossini's 'William Tell' has a famous one
• Rossini's "William Tell" has a famous one
• Musical piece given in public, by river
• Opening plain remedy to banish cold
• In a common classical concert programme format, a work by Franz von Suppé is very likely to be the ____
• Score starter
• Orchestral opener