Thongchai Jaidee, James Kingston and Alastair Forsyth share second place at minus-5. Twelve players, including Justin Rose, Jose Maria Olazabal and Ian Woosnam, are tied for fifth at 4-under-par 68.
Clarke began his round on the first tee on the West Course at the Wentworth Club. He started smoothly with eight consecutive pars and got on the board with a birdie from eight feet out at the par-4 ninth.
Around the turn, he rolled in back-to-back birdies from the par-4 11th to move to minus-3. Clarke's momentum stalled briefly as he notched four straight pars.
However, he leapt to the top of the leaderboard by closing with an eagle on 17 and a birdie on 18. He rolled in a 18-footer from the back of the green at No. 17 for the eagle.
'I'm pleased after the start,' said Clarke. 'I was patient all day and a few good things happened at the end. I had quite a few putts today, but I was very patient.'
Clarke knows the great history and tradition of this tournament and would love to add a victory here to his resume.
'It's high on everybody's portfolio to win. It's the Volvo PGA Championship and one we all want to win,' Clarke said. 'Certainly I would love to get an opportunity to win this week. There's an awful long way to go, but I'm pleased to get off to the start I have.'
Kingston stumbled out of the gate with a bogey at the first. He recovered quickly to birdie the next and the South African rolled in another birdie at the par-5 fourth. From there, he parred out the front side to head to the back at minus-1.
'I bogeyed the first but recovered after that and got through the first three holes at even par,' said Kingston. 'I birdied the fourth which got me in a nice, positive frame of mind for the rest of the round.'
He caught fire on the back nine and jumped up the leaderboard with three straight birdies from the 10th. He moved to 5-under with a birdie at the 14th, but faltered at the next.
On the par-4 15th, his tee ball found a ditch and he struggled to a double-bogey. Kingston got back into contention with birdies on each of the final two holes.
'The back nine just started wonderfully, making the three birdies in a row,' Kingston said. 'Then I got an unfortunate break on 15. I didn't hit a good tee shot and it landed in that little ditch and I ended up making double-bogey. But then I finished nicely with two birdies so I was pleased with it.'
Forsyth had a bogey and two birdies on the front nine. Around the turn, he followed Kingston's roll with three straight birdies from the 10th. He dropped a stroke with a bogey at the 13th before closing with back-to-back birdies.
Jaidee struggled to begin his round. He bogeyed the first but responded with two straight pars. Jaidee then notched consecutive birdies from the fourth before settling down and converting nine straight pars.
Jaidee closed in fine fashion. He birdied the par-4 15th, then eagled the par-5 17th. He followed that with another birdie at the last to join the tie in second place.
Ernie Els and Colin Montgomerie are among 19 players tied at 3-under-par 69. Defending champion Anders Hansen is one stroke further back at minus-2.