Possible Clues:

• Predict that this is a sound C following 4
• Warning, of course. Look, one can predict it
• Number said to understand and know beforehand
• Intellectually challenged class said to enjoy prior perception
• That might be a profitable thing to do, by the sound of it (7)
• Expect charge for carrying minerals
• Anticipate noise made by third-stream class
• Be profitable, perhaps, by the sound of it
• To know beforehand
• Might, by the sound of it, a quartet overlook 9 across