### Clue: Protected customers sounded off endlessly about goods? Quite the opposite! (10)
### Answer: WARRANTEES 
 ### Explanation: Definition: Protected customers
An envelope ('about', with the particles exchanged by 'quite the opposite') of RANTE[d] ('sounded off') minus the last letter ('endlessly') in WARES ('goods'). A warantee is a customer to whom a guarantee is given.