The Blues boss admitted that his players simply weren't competitive enough, particularly in the first half of the game.
Jermaine Beckford struck on 25 minutes with the only goal of the match. Although Blues had a handful of chances to level the score, that would have been unfair to a Huddersfield side that were generally brighter, more competitive and showed a greater attacking threat.
"I thought in the first-half we handed the initiative to Huddersfield and we weren't competitive enough," said Clark. "Or certainly we didn't have ten outfield players who were competitive enough.
"I know it takes all kinds to make up the facet of a team but all outfield players have to take responsibility and compete with their opponents and come out with a 50-50 on the odd occasion. In my view, Huddersfield came out with them all - all the big ones, and they were left running at my back four players.
"We tried to have a go in the second-half. We brought Nikola Zigic on and he did well. I was pleased with that, but then he got sent-off. Whether it was a sending-off or not is debatable?
"The lads then had a go with ten men, so why not have a go from the first whistle?"
After the improved showings against Brighton and Cardiff on their travels, Clark was particularly disappointed with his players' showing in front of their home crowd.
"It's our home and it's where the majority of our fans come to see us and they want to see a performance," he said.
"Any football fan in the world wants to see a bit of drive. Football fans are working class people they want to see someone having a right good go for their team in terms of tackling, heading, competing. There were four or five players in the first-half who never did that and they have got to stand up and be counted. They can't just hide behind me all the time; they have got to come out fighting."