Possible Clues:

• The four parameters often describing a sound in electronic music are attack, decay, ____, and release
• Suffer in South American train, right away
• In Sun it's a knitted bear
• Support America in incident damaging reputation
• Feed, nourish
• Support America in smear
• Continue, prolong
• Spot invaded by American bear
• Confirm Mark is touring the States
• Experience open-top bus in colour