As was said above, he was being intentionally deceptive to the committee, but he did not tell an untruth. The commission should make hay over it, but it won't put Clarke in jail.
I've sort of been sitting back watching all this happen. Then today, I unfortunately caught an puff piece interview with Clarke on CNN today. In that interview, he was so incredibly slimy that I simply could not sit back and take it anymore. He deceptively implied that the Monica Lewinsky investigation (ie. the Republicans) and accusations of "Wag the Dog" prevented Clinton from taking out UBL and AQ.
It is a fact that Clinton used military action to divert attention from his investigation. The 1998 attack on Iraq began on the very day that official impeachment hearings were to begin in the House of Representatives. The attacks on Iraq stopped the very day that the hearing ended. Then, on the very day that Monica Lewinsky appeared in court for her testimony, Clinton attacked the Sudan and Afghanistan.