Answer:
Mandela injured the player at the gym with a venomous bite.
Step-by-step explanation:
Clue 1: 6 - The victim was not poisoned by chemicals
Clue 2: Egypt - Gandhi was diluting juice in the kitchen
Clue 3: Music and dance - The victim was not mauled by a cougar
Clue 4: 9 - The victim was not electrocuted
Clue 5: Mafadi - Du Toit was sweeping the theater
Clue 6: Atlantic and Indian - Barnard was fixing the wooden flooring in the library
Clue 7: Nelson Mandela - Pieterson was playing Uno in the atrium
Clue 8: Kalahari and Namib - The injury was not a stubbed toe
Clue 9: 11 - The victim was not hit by a fallen object
Clue 10: Johannesburg - Fassie was sleeping by the pool
The only person, place, and cause of injury left are Mandela, the gym, and a venomous bite.