He came within a few punches of doing much more than that Tuesday night at ExCel South Arena 2.
With a semifinal appearance and a guaranteed medal on the line, Clayton fought European champion Freddie Evans to an even 14-14 score but the Brit won on a countback to advance.
"I thought I dug down and got it," Clayton said. "But hey, nothing I can do."
The countback is used to break scoring ties. Officials count the number of punches thrown in the fight and the boxer with the higher total wins. The final punch statistics aren't normally released.
The Canadian team filed a protest later in the evening but it was rejected by the International Amateur Boxing Association, according to the team's media attache. The Canadian team said in the failed appeal that Evans should have been given a warning after receiving a third caution for the same foul.
A warning gives two additional points to the opponent. The venue's media manager said officials planned to review the video, but there was no immediate word on when a decision would be announced.
Clayton earned Canada's first Olympic boxing victory in eight years when he defeated Mexico's Oscar Molina 12-8 earlier in the tournament. He followed that up with a 14-11 win over Cameron Hammond of Australia.
The raucous crowd was energized for Tuesday's quarter-final bout. The spectators roared when Evans was introduced and quickly began chanting his name.
The fight looked like it would be a rout early on.
Evans stormed out to a 7-2 lead after peppering Clayton with punches, including a big overhand left with a minute left in the first round.
The Dartmouth, N.S., fighter changed tactics in the second round. He moved his body more and often dropped down before springing up and attacking.
The changes worked as Evans lost his rhythm. Clayton took the round 6-3 and was right back in the fight.
The Canadian came out swinging in the final round and had the Brit back on his heels. Clayton was determined to be the aggressor and it nearly paid off.
Evans seemed overwhelmed in the final minutes and was clearly playing defence.
"I had a big first round but I knew he was going to come back and put the pressure on," Evans said. "He smothered my work a bit, and he's a top experienced fighter so it was always going to be a tough fight."
Clayton summoned every bit of power from his chiselled physique to go after the Brit. He was fighting to win while his opponent was just trying to hang on.
Before the decision was announced, both fighters raised their hands thinking they'd won the fight. The sellout crowd in the 10,000-seat venue popped when Evans was given the victory.
Clayton, 24, seemed satisfied with his effort and took the loss in stride.
"I'm not going to complain too much about the decision," he said. "I thought I fought a great fight."
Evans felt he was ahead by a point or two.
"I knew I had let him come back into it, but I thought I was ahead," he said. "Then it came to the countback and I was very scared. That was the biggest moment of my life in there, but I always did think I had the edge."
Canadian coach Sylvain Gagnon said he told Clayton not to panic after the first-round barrage. He suggested staying in close to Evans to take away his long jab.
"The third round was for me, in my book, he had the fight," Gagnon said. "But it was (such a) close fight. You have to fight against the crowd and against the fighter."
The other Canadian boxers in London were eliminated Monday. Simon Kean of Trois-Rivieres, Que., and Mary Spencer of Wiarton, Ont., both lost their quarter-final fights.
Canada has struggled in boxing at recent Games. The last Canadian to win Olympic boxing gold was Lennox Lewis at the 1988 Games in Seoul.
It was a solid showing from Clayton, who finished 17th at last year's world championships.
Gagnon said he likes where the national program is going.
"I think the next Olympics, we're going to do better and better," he said.