Clarke was alive as Burton switched off when Callum Robinson’s cross looked to be going out for a goal-kick. The Preston skipper refused to give up and scooped the ball back across goal and inside the far post – to the surprise of almost all inside the Pirelli Stadium.
The goal was very much against the run of play but a reward for not giving up on a lost cause and another lesson to Nigel Clough’s side, who also conceded in added on time in the reverse fixture at Deepdale back in November.
The Brewers are now looking nervously over their shoulder just a point outside the relegation zone after results elsewhere went against them.
Albion had the better of a tame first half where neither goalkeeper was seriously tested as both sides favoured the more direct approach.
Jamie Ward audaciously tried to lob Chris Maxwell in the Preston goal from distance early on and was later denied what would have been a tap-in by an excellent intervention from Preston’s Australian international Bailey Wright on the edge of the six-yard box.
Tom Naylor was inches away from heading home a Matt Palmer corner as Burton continued to have the better of proceedings – but they fell victim to another stoppage time goal when Clarke pounced at the back post.
Lucas Akins squandered a chance early in the second half as the hosts introduced new signing Marvin Sordell at the break.
Eoin Doyle saw a header comfortably saved by Jon McLaughlin and Jordan Hugill, peeling away at the back post, lashed a shot wide of the target as Preston showed more attacking intent after the break.
Daniel Johnson pounced on a poor pass by Burton skipper John Mousinho to set up the overlapping Robinson but his shot produced an excellent save from McLaughlin.
Sordell showed great skill to control a Palmer pass and saw a left foot drive blocked to deny him of a debut goal as Albion continued to battle for an equaliser.
Jordan Hugill rose highest at the back post to meet Johnson’s deep cross but he wasted the chance to put the game beyond Burton, heading wide.
Greg Cunningham came to Preston’s rescue late on, clearing Matt Palmer’s cross off the line just as substitute Marcus Harness looked primed to notch his first senior goal after coming on as a substitute.
A Preston side who have only conceded one shot on target in two games and playing their second game in 48 hours were not tested again and saw out what remained for a gritty but not overly spectacular victory.