Centre-back Neill Collins headed the only goal after just five minutes at the Galpharm Stadium on Tuesday night as the Blades moved up to second in League One.
"We have had a lot of pressure and created chances but it didn't happen for us," said Clark.
"We have to take it on the chin, dust ourselves down and go again."
Town have no match on Saturday and Clark admitted: "I would have liked a game to get this out of our system but it's not to be.
"We have to bounce back but we can take heart from this performance. We have lost the game but hopefully we can continue with this type of performance."
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