The protected big cat was shot and killed by U.S. dentist Walter Palmer during a hunting trip to Zimbabwe and the story sparked outrage around the world, with many celebrities, including Delevingne, condemning Palmer and other trophy hunters.

The catwalk beauty is now taking action by selling off her worn TAG Heuer watch on auction website eBay.com to raise money for researchers at Britain's Oxford University's WildCRU, or Wildlife Conservation Research Unit, who were studying Cecil for years before his death.

Delevingne writes on Instagram.com, "The killing of Cecil the Lion was a tragedy. Today join me to help the scientists who care about the future of wild lions in Africa and work very hard on their conservation. Ahead of the official sale of my TAG Heuer Signature Edition watch, I decided to auction my personal timepiece... I wore this watch on several occasions and during the last Monaco Grand Prix. The full amount will be refunded to WildCRU.org, the research unit that followed Cecil for many years. So let's join forces!"

The auction closes on 10 August (15).