Herd made his comeback in last weekend's defeat at Fulham after 11 months out with various injuries.
"He did very well on Sunday and no-one could have asked any more of him," Clark told the club's official website.
"We've got a big enough and a good enough squad where if there are injuries people can come in and fill in and do a good job.
"There's competition all over the squad but with the training everyone is looking to make a mark and get themselves on the teamsheet.
"It's a competitive edge we have in the week so when it comes to the games we're very much together and want each other to do well. It's very positive to us."