Clough said: "We have to win one out of last three games - or at least get a couple or draws - if we want to be okay.
"We didn't take our chances, especially the one that fell to Rob Hulse in the 94th minute.
"I thought we had got to grips with the game in the second half but I think they had a feeling of injustice over the sending off and that seemed to galvanise them."
Palace manager Neil Warnock admitted that Moses' sending off was the turning point and insisted referee Andy Woolmer made a big mistake.
Moses was booked for diving on the stroke of half-time and then collected a second caution for a foul on Mile Sterjovski when he appeared to play the ball.
Warnock said: "The referee got it completely wrong. Victor was touched for the first one and then he played the ball for the second.
"But the sending off won us the game. It seemed to give us more urgency."
Warnock added: "Shefki Kuqi worked his socks off and he capped it off with a great goal.
"Overall it was a great effort by us when you consider all the injuries we had."