Yannick Bolasie's 13th-minute goal condemned the Rams to their first home defeat of the year, but the visitors were forced to repel a second-half onslaught, culminating in Conor Sammon's penalty being saved by Julian Speroni.
"We can't ask much more from the players, not just the effort but the level of performance," said Clough.
"To come off without so much as a point for our efforts is very harsh on the players.
"We've got to improve a bit on our finishing, but we're not getting any breaks in the penalty area.
"We've got in some great positions and put lots of good crosses in - the players have done nothing wrong."