The Saddlers reached the match on the back of a midweek EFL Trophy defeat to Portsmouth but were yet to taste defeat in the league following wins over Leyton Orient and Salford City.
However, goals from Max Sheaf, Conor Thomas, and Alfie May saw promotion-chasing Cheltenham secure a welcome - and all-too comfortable - win in front of over 3,800 fans at the Jonny-Rocks Stadium.
Cheltenham didn't have it all their own way as the Saddlers got on the scoreboard as second-half substitute Elijah Adebayo bagged his fifth goal of the season, but Clarke admitted he was disappointed following an awful first half.
When asked whether his team had entered a disappointing display, Darrell admitted; "It was. We can’t paper over that. I thought for the first 45 minutes we were awful, if I’m honest.
"Kicking it long, ball going out of play, no-one making angles to get on the ball. We didn’t look like a team that’s been doing well recently. Cheltenham are a good team, obviously, but we sort of played into their hands.
"We were very, very sloppy in our performance. We were very lethargic in our performance. Then we changed things around a little bit second half and we give another real cheap goal away.
"It doesn’t give us a chance to build and the players have got to learn from that. I’ve been very critical of my players previously and like I said to them in there, one in 10, I can handle it.
"I’m not happy, obviously, very disappointed. But you have to take your medicine in those situations. We got beat by a better team today and my team didn’t turn up."