Anthony Pilkington had given Town a 1-0 lead at The Galpharm Stadium on Saturday but a late Ben Marshall equaliser gave Carlisle a share-of-the-spoils on Saturday afternoon.
"We looked nervous, particularly in the first half, and I don't know where that came from," Clark said.
"This was a chance to play in front of a big crowd for a club that wants to win promotion. The team has been a bit hit and miss lately.
"Too many players have been up and down. We've not seen the level of consistency from the players recently that they showed earlier in the season.
"I'm not sure whether I'm expecting too much. A lot of the players are still young. But I grew up with this level of expectation at the club where I was at this age.
"If the performances were not acceptable then we were told in no uncertain terms every time we went out to the supermarket.
"The players here are going to have to get used to that level of expectancy. We have to look at the positives though.
"This was a game we could have easily lost. We have to look at it as a point onto our tally and take it from there."