Clubmans Sports Prototype dominator Clarke continued his impressive form by winning the opening two races in Leicestershire, but he was denied another clean sweep after an electrical fault on his Phantom PR22 in the finale.
Nevertheless, it was still enough for him to retake second on Autosport's leaderboard and close to within two victories of leader Freddie Slater's 14 wins.
However, another Clubmans competitor did complete a treble as Mathieu Gauthier-Thornton picked up another three CSP2 class triumphs in his Phantom P94, which have sent him storming up 25 places and into 11th.
Elsewhere, Lucas Romanek has scored National and United Formula Ford 1600 victories already this season but ended Felix Fisher and Luke Cooper's stranglehold over the Castle Combe championship last weekend.
The 10th win of Romanek's campaign enables him to climb from 10th to fifth in the rankings.
Aidan Hills, the Mazda MX-5 star who topped the table earlier this year, also added another win over the weekend, this time a class success at the wheel of a Ginetta G40 GT5 in the Trackday Trophy at Donington.
But it was not enough to stop Hills from sliding down the leaderboard, Romanek relegating him to sixth spot.
Source: Autosport