They made the charge at a forum organised by social enterprise support organisation Can Mezzanine to discuss issues such as business support, loan funds and the delivery of social services.
Social entrepreneurs told the Tory politicians that existing social financiers needed to be more daring in their investments. Clark, the shadow charities minister, agreed that innovation meant an element of risk.
"For there to be progress and dynamism, you have to have the possibility that things can go wrong and to understand that not every failure is a culpable failure," he said. "There are times to take risks on a well-informed and intelligent basis. For every one that goes wrong, there will be five that show a real social dividend."
Adele Blakebrough, chief executive of Can, said: "It's heartening to see that the shadow cabinet are interested in the third sector and trying to tease out the issues."