But Knights, who have three wins from four starts, had to dig deep to see off a Bedford side who are clearly in a false position in the bottom two.
The result was in the balance until Knights, leading 23-22, scored their bonus point try four minutes from time.
It was a try worthy of winning any game with full-back Paul Jarvis showing both pace and determination to make the line after backing up a blistering midfield break by wing Tyson Lewis. Recalled wing Dougie Flockhart added the extras.
The Blues had looked capable of inflicting a rare home defeat on the Knights when scoring twice in quick succession to lead 22-18 midway through the half.
Ollie Dodge broke down the middle before sending fellow centre Tom Farrell over on 58 minutes.
Prop Jacob Fields touced down from a forward drive shortly after Clark had been sin-binned.
Bedford’s hopes of hanging on to their lead weren’t helped when flanker Ben Adams was sin-binned on 70 minutes and Knights cashed in on their numerical advantage with flanker Latu Makaafa capping a hard-working display when touching down from a forward drive to restore their lead.
Knights had earlier opened the scoring with a seventh-minute penalty by Flockhart who then touched down in the corner after Jarvis, who had looked all set to score after beating several defenders before being nailed just short by Hill, managed to pop the ball up to the Scot.
Fly-half Jake Sharp latched on to a stray pace as Knights looked to run the ball out of defence, and raced in from 30 metres to score.
Bedford finished the half well on top and their efforts were rewarded with a close-range try by Hill on the stroke of half-time. Knights regained the initiative after the break and Clark ran a superb line to score after skipper Michael Heaney picked him out from a scrum on the Bedford 22.
The home side could have gone on to put the game to bed in the third quarter.
Clark had a try disallowed for what must have been a marginally forward pass and Flockhart opted to take the ball in rather than make use of a huge overlap to his left.
Doncaster Knights: Jarvis, Flockhart, Clark, Hayes, Lewis, Cusack, Heaney, Hislop, Allen, John, Nolan, Young, Makaafi, Robinson ,Shaw. Rep: List, Hunter, Quigley, Challinor, Scanlon, Humberstone, Edgerley.
Bedford Blues: Le Bourgeois, Tapley, Farrell, Dodge, Adamson, Sharp, Burns, Thompson-Stringer, Edgson, Spelman, Howard, Carrick-Smith, Blanchet, Adams, Hill. Rep: Field, Parilli-OCampo, Walker, Taylor, Buggea, Whiteley, Dorrian.
Referee: John Meredith.