Miss Clark, who is the Administrator of the UN Development Programme, is ranked 34th on the list, up from 50 last year.
Topping the list, for the second year running, is German Chancellor Angela Merkel, followed by US Secretary of State Hillary Clinton then Brazil President Dilma Rousseff.
Microsoft billionaire Bill Gates' wife, Melinda, who co-chairs the Bill and Melinda Gates Foundation, is ranked fourth.
The youngest entrant on the list is 26-year-old singer Lady Gaga, who made it to number 14 on the list.
The oldest, at 26th, is the Queen, aged 86.
Talkshow queen Oprah Winfrey comes in at 11, singer/actor Jennifer Lopez is 38th, comedian Ellen DeGeneres is 47th and actor Angelina Jolie is 66th.
The women's nationalities span 28 countries and represent fields such as politics, business, media, technology and non-profit organisations.
Their positions are determined by calculating wealth, media presence and overall impact.
Others to make the top 10 include New York Times editor Jill Abramson, Indian politician Sonia Gandhi, United States First Lady Michelle Obama and US Department of Homeland Security Secretary Janet Napolitano.
