I named my toy monkey, Clarence, after the loveable lion. I was born in 1963 and this film was out in 1965 so I don't know when I saw it as it must have been in a cinema.
I always thought it was a television series until I did a quick search to see that it was a film instead. My poor monkey is a threadbare pink toy now and he's lost one of his rubbery ears and a hand. The ears, hands and feet were plastic and the body was soft. Well, he's not bad for 45 anyway!
(I was just wondering if there was a chimp character in the film?)
In the film, Dr. Marsh Tracy, head of an African animal behavior center, captures an oddly placid lion whom he names Clarence. The beast's eyes as it turns out, are crossed. When Dr. Tracy and an anthropologist are kidnapped by poachers, Clarence shows his paws, jaws and claws work superbly.
They don't make 'em like they used to!