The five cubs, born in June, leave their den having spent their first weeks tucked away.
Lion Aid, which is based in Dover, is providing flashing lights to keep wild animals from villages.
Sahee quickly won the hearts of his keepers when he first arrived last year, the zoo says.
"The only difficulty was doing it on a lion, and not your regular moggy," says a vet.
Autopsies show that the lions suffered from dehydration and multiple organ failure.
The 16-year-old, which had fathered three cubs, moved to his Suffolk "retirement home" in October.
Their mum has been "so attentive, making sure her cubs are fed, clean and comfortable", a zoo says.
Clarence and his brother Brutus were rescued from a French circus in 2012.
