For the next 20 months Clark's workload includes keeping the heat on progress towards the Millennium Development Goals (MDGs).
Nearly 200 nations agreed in the year 2000 to the eight ambitious goals. Many of the UNDP's tasks are geared to achieve them, including the herculean aim of halving poverty by 2015 at a time of global financial crisis.
Clark, who was Labour Prime Minister for nine years, insists the chances of seeing poverty halved are "quite high". But she accepts that would still leave hundreds of millions of "extremely poor people".
"I hope that eradicating extreme poverty might be accepted as a top target for the next generation of development goals."
Clark, who started the UN job in April 2009, is more than halfway through her four-year term. She is a heavy hitter in the giant UN bureaucracy, effectively number three in the organisation.
She seems to have earned aid credibility: a Guardian list of leading development figures published in September ranked her in the top 10 "interesting people" to follow on Twitter.
Given the size of Clark's fiefdom, it is no surprise that the UNDP, which has a US$5 billion ($6.4 billion) budget, cops its share of flak. This year a UK Government review of aid concluded the UNDP had "weak" cost control, though overall it gave the agency a "good" grade.
Clark notes that her agency's grade was the same as UNICEF's, and higher than others. But she wants to a "good to great" and had started a shakeup before the review.
From her New York base, Clark is never far from her Kiwi roots. She stays in touch using Skype, Facebook, Twitter, news websites, phones, and email.
"There's not much I don't hear about from family and friends," she says.
Take it as read that she has more than a passing interest in the battle to succeed Phil Goff as Labour Party leader. Contender David Cunliffe has acknowledged that he had a discussion with Clark about the job, but she remains tight-lipped.
Asked if she had a pick, she replied: "Not for public consumption."
REMARKABLE ACHIEVERS
They have made our country a better place in 2011 - welcome to the Herald's New Zealander of the Year series. This week we're profiling 10 finalists. So far we have featured the Rena salvors; Sam Johnson, leader of the Christchurch earthquake student volunteer army; World Cup boss Martin Snedden; Kimberley White, who stood up to her mother's killer; All Blacks captain Richie McCaw and road policing
manager Paula Rose. We'll announce the overall winner in Saturday's Weekend Herald, along with the best sporting achievement and business leader of the year.