After a 1-0 win over Austria in Vienna in their last group game Scotland are second behind runaway leaders Denmark, four points clear of Austria and one point above Israel with the play-off spot in their own hands.
Scotland host Israel on October 9 and visit the Faroe Islands three days later.
Boss Clarke said: "We have put ourselves in a good position but there is no point in talking about what we can and can't do, we have to do it on the pitch. Let's see what the next two games bring.
"When you are getting to qualification for a World Cup finals, you want to do as well as you can so you have to pick up points in every single game. There is no other way to look at it.
"Every game when you are playing for your country or managing your country should be treated like a cup final because you always want to do well for your country."
Clarke insists he had no qualms about including midfielders Callum McGregor and Stuart Armstrong in his squad.
The Celtic captain has missed the Hoops' last four matches with a hamstring injury while Armstrong, who has not played a minute for Southampton this season, returns having pulled out through injury ahead of the 2-0 loss to Denmark earlier in the month.
The former Scotland defender said: "When you name a squad there is still 11 days until matchday so plenty of time, a couple of games.
"Callum is in that situation, Stuart Armstrong is in a similar situation but I am hoping that they will both get some minutes over the next couple of games and be fit and available to join the squad.
"The medical staff have been in constant touch, we know where the players are at and as always we will treat them as well as we can."
Manchester United midfielder Scott McTominay is also back in the squad after he needed groin surgery last month which forced him to miss the triple-header against Denmark, Moldova and Austria.
Clarke said: "It's good to get as many of your better players in the squad as possible. Scott is certainly one of those so it is good to have him back."