Despite losing their last two matches, the Baggies remain eighth in the Premier League thanks largely to an impressive first-half of the season.
Clarke has urged his side to rediscover that form in their last six matches.
"There are a lot of teams below us who would like to be sitting where we are just now, with the confidence and security of knowing they are in the league next year," he said.
"The work we did in the first-half of the season is paying dividends now but it is important we don't let the season just drift away.
"I said in the first half of the season that you have to balance the season as a whole.
"It doesn't matter when your good spell is, you will always have one. We had a prolonged good spell and we are getting the benefits now.
"It has been a reasonably good season for us. We don't want it to just fizzle out. We don't want the last six games to drift.
"We have to give ourselves a target. One win would give us a record number of home wins in the Premier League. We would also reach 47 points, which was last year's total. It would bring us closer to 50 points.
"But I don't want to settle for 50. We have six games left. There are 18 points up or grabs. We have to get as many as we can and finish with as many points as we can."
Clarke confirmed Peter Odemwingie would miss the Newcastle game with a knee injury, whilst 16-year-old Izzy Brown, who was on the bench against Arsenal a fortnight ago, is also struggling.