A first half of few chances was almost lit up by Thomas Ince five minutes before the break when he raced away from two defenders before letting fly from the edge of the box, only to slice his shot wide.
The visitors came close to breaking the deadlock five minutes after the restart when Kirk Broadfoot's deep cross was met by Angel Martinez, but the Spaniard's header drifted narrowly wide.
Iain Hume almost gave the hosts a lead shortly after the hour mark with a fine strike from a tight angle, but Matt Gilks produced an equally impressive save to tip it wide.
Michael Chopra was the next to come close when he did well to get on to the end of a cross, but his header bounced off the pitch and looped on to the roof of the net.
It was Preston who struck the killer blow late on, however, as Clarke ghosted in at the far post to nod a Lee Holmes free kick past Gilks from close range, knocking Blackpool out in the process.