Worcestershire Rapids went down by eight wickets to local rivals Warwickshire in a Royal London One-Day Cup encounter at Edgbaston.
The front-line Worcestershire batting line-up was undone by an excellent spell from Clarke who bowled his 10 overs unchanged in returning career best List A figures of 5-26 from 10 overs.
Ed Barnard top-scored with 38 as Worcestershire were dismissed for 115 in 38.2 overs.
There was then the encouraging sign of Charlie Morris picking up two front-line Warwickshire wickets after his tireless work on attempting to successfully remodel his action.
But the home side, beaten in both NatWest T20 Blast encounters with Worcestershire this summer, reached their modest target after an unbroken stand of 79 off 65 balls by Tim Ambrose and William Porterfield.
Tom Kohler-Cadmore drove the first ball of the match from Clarke for four but it was his only scoring shot before he nicked the final ball of the over to Laurie Evans at first slip.
Keith Barker shared the new ball and trapped Tom Fell lbw for four in his first List A innings of the summer.
Clarke then took centre stage as Alexei Kervezee was bowled for nought and skipper Daryl Mitchell (10), Ross Whiteley (0) and George Rhodes (0) all were dismissed lbw to leave the score on 19-6.
Five wickets went down for two runs before Ben Cox (10) and Joe Leach added 22 until the former was caught by Hain at cover off Recordo Gordon.
The major stand of the innings saw Leach and Barnard add 60 in 18 overs to take the total past 100.
Barnard continued his recent impressive form with the bat and straight drove Gordon for four and cover drove Barker to the boundary.
Leach made a determined 29 off 65 balls before he was bowled by Oliver Hannon-Dalby and then Barnard's accomplished 38 ended when he was caught and bowled by Jeetan Patel.
He struck six boundaries in his 64 ball knock. The innings ended when Jack Shantry (3) holed out to mid-off off Patel.
When Warwickshire replied, Morris came into the attack first change and dismissed Sam Hain and Jonathan Trott in successive overs.
Hain (21) nicked a fine delivery through to Cox and then Trott (4) was lbw to leave Warwickshire on 40-2.
But Ambrose (54 not out) and Porterfield (37 not out) saw Warwickshire to victory in 22.4 overs.