Centre-back Clarke, 18, curled in a superb shot with the outside of his right boot on nine minutes after Martin McIntosh flicked on Danny Schofield's corner.
It was the first goal Huddersfield had scored at home since Andy Booth's header against Nottingham Forest on November 26th and Clarke was denied a second one soon after by Blackpool keeper Lee Jones' parry.
Clarke, who was pressed into service as a midfielder against Chelsea in the FA Cup last week and did so well in marking England star Joe Cole out of the game that he retained his place, was outstanding throughout and created several chances for other players.
But Pawel Abbott, Andy Booth and Schofield were not able to convert Clarke's through balls and crosses.
It needed a penalty awarded on 72 minutes for Marc Joseph's trip on Jon Worthington to seal the win.
Schofield's spot-kick was brilliantly saved by Jones but the ball spilled away from the keeper and he was the first to react to the rebound.
Blackpool, who have won only twice away from home all season and are locked in a tough relegation battle, attacked on the break and created several clear cut chances.
The visitors were denied what looked like a certain goal when Town keeper Paul Rachubka clawed John Murphy's close-range header over the crossbar on 15 minutes.
And just before half-time, Keith Southern put Keigan Parker clean through with a defence splitting pass.
Seven-goal scorer Parker expertly controlled the ball and beat the advancing Rachubka but his shot flashed wide of the left-hand upright.
From there, manager Simon Grayson used all three substitutions after the break in an effort to bring the Seasiders back into it but it failed as Blackpool managed only one shot on goal in the second half.