"It takes a while to get over these things because I hate losing so much," he told the Northampton Chronicle.
"We've got a final on Saturday but it's not easy to get over these kind of losses.
"We want to be a great side, push on and do great things, but on Saturday we fell short."
Clark who made the move to Franklin's Gardens from Leeds Carnegie last summer has played in seven of Northampton's Heineken Cup games this season and is under no illusion how important Saturday's final in Cardiff is for the club.
"We've got to win the final, that's the most important thing," he added.
"We're not here to be finalists or to be runners-up, that's not what we're about, so we've got to get our heads around winning on Saturday.
"It's a final, a one-off game and we will give it everything.
"Saturday's our last game of the season.
"We've got nothing to lose and the Heineken Cup to gain so that's what we'll focus on."