Australia were 494 for seven when a storm swept in on the back of high winds and prevented any play after mid-afternoon. (Agencies)
Before the rain, Australia were on target to take their total past 500 and subject South Africa to a challenging examination from the tourists' fast bowlers in what was shaping as a mirror image of the domination achieved by South Africa in the second Test in Port Elizabeth.
Clarke said it was a "very satisfying" innings. "There were some tough stages yesterday (Saturday). Morne Morkel bowled a couple of pretty quick spells, bowling around the wicket with a set plan to attack the emblem on my helmet.
"That was difficult to get through but most important is we've got 494 runs on the board and I'm extremely pleased with the position we're in."
Clarke said Australia were determined to push for a win which would seal a series that is tied at one match each.
He said there was some inconsistent bounce. "Hopefully it continues to deteriorate and gets a little more up and down. But we're going to have to bowl well, it's still a very good batting wicket."
South African bowler Kyle Abbott, who bowled two tight spells in difficult, windy conditions, said he thought the pitch would stay good for batting through most of the rest of the match.
"We've got to bat as well as they have," he said. "We have to keep positive. As soon as you start thinking of a draw, or any negative thoughts, you come unstuck."
Australia scored 163 runs in 39.4 overs on Sunday, blunting a depleted South African pace attack with an almost-new ball at the start of the day and then going for their shots.
Australia were 494 for seven when a storm swept in on the back of high winds and prevented any play after mid-afternoon.