While ministers had no plans to change the law on 11-plus selection, he said, this was "bound to be a consideration as the Government moves forward".
Those campaigning to end the 11-plus have complained that the rules make it virtually impossible to win a ballot to scrap a grammar school and campaigners will hope Mr Clarke's comments signal a willingness to address this.
In the short term, he told MPs on the Commons education select committee, authorities with grammars needed to assess whether the system raised or damaged standards overall. He said that selection arguments should not be fought on "ideological" grounds alone, but over the effect on standards.
Commenting on the pre-comprehensive system, Mr Clarke said: "The bottom line is that selection resulted in a system...which inhibited educational opportunities for significant numbers of people. One of the great successes of comprehensive education was that it eliminated that problem."
The Education Secretary also coined a new expression: the "comprehensive-plus" system. Comprehensives had sprung up in opposition to the 11-plus, he said, and millions of children had benefited. But perceptions around the word "comprehensive" suggested an approach which was less focused on the needs of the individual child.