Clough says the diminutive forward's absence is felt more in away matches, with Derby having lost their last four games on the road.
Ward has been sidelined since limping off with a hamstring injury during the 1-0 win at east midlands rivals Nottingham Forest on September 30.
The Northern Ireland international has missed the last dozen Championship fixtures and will remain out when Leeds visit Pride Park on Saturday, despite having an injection this week in an attempt to aid his recovery.
Derby have played six away fixtures during Ward's absence, winning once and losing four times and scoring just six goals.
"We are struggling to score away from home," said Clough. "Not having Jamie Ward makes a difference, we've really noticed that he's not there in the away games.
"He is a creative player and is particularly important in away games. He can make something from nothing and get you a goal when you really need it, like at Leicester last weekend. We haven't been able to work out how to do that in away matches recently."
Ward will miss his 13th game on Saturday and Clough does not know when he will have the 26-year-old available again.
"Do we have any idea when he will be back? No, not yet," said the Rams boss. "And that's the huge frustration for him - and for us.
"It will have to be 100% right before he comes back, so it's just a matter of remaining patient."