Trump is smart with this strategy. Whether Clapper has directly admitted or not, he was most definitely involved as a ring-leader, and Clapper has parsed his words and lied before
Get it out into the public and associate “Clapper” with “domestic spying” and “coup plotting”
As LBJ said: “I just want to hear the son-of-a-bitch deny it.”
IIRC, it was Clapper who gave instructions to Comey as to what should happen at his first private meeting with the President.