But it wasn't because of Scotland's opponents.
The Scotland manager sat in anticipation as the teams were revealed, learning who his side would have to face in their quest to qualify for their first World Cup in 28 years.
The Tartan Army were drawn into Group C alongside Greece, Belarus and the loser of Portugal or Denmark.
Cristiano Ronaldo could be the country's enemy number one if he scores to rip up Scotland's ticket to the United States, Canada and Mexico.
That match, which will decide whether it will be Portugal or Denmark in Scotland's group, will be played across two legs on 20th and 23rd March.
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Clarke admitted after the draw that he was not sitting comfortably as the teams were being read out.
But it had nothing to do with Scotland's group opponents - it was his chair.
Clarke joked: "I thought the seats were really uncomfortable. My backside is killing me."
He continued: "You always just have to take the draw you get. Obviously either Portugal or Denmark are both tough games.
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"We now play Greece four times next year so we'll get to know the Greeks very well. So yes, reasonably happy, but it's always difficult.
"We play competitive matches home and away against Greece. So, we get a good look at each other in March and then we'll meet each other again September, October, November.
"We'll be looking for a couple of friendlies in the summer to get through the summer and fulfil our fixtures. But, no, listen, it's an exciting year to look forward to."
When asked what it would mean for Scotland to qualify for the World Cup Clarke replied: "Well, we haven't been to a World Cup since 1998.
"That sounds like a long time when you say it, because in 1998 I was still playing. So, that is definitely a long time ago. So, it would be nice to put that right."
The manager stated it 'would be good' to qualify for back-to-back tournaments, referring to Scotland's participation at the 2024 Euros in which they faced Germany in the opening match.
They also played the opening match in France 1998 as Craig Brown led Scotland against the champions Brazil.
Unfortunately they did not get through to the knockout round thanks to a draw and two loses, including a 3-0 loss to Morocco when Craig Burley was sent off in the 54th minute.
They didn't fare much better at Euro 2024, either, where they were thumped 5-1 by the Germans, before a 1-1 draw with Switzerland and an agonising 1-0 defeat to Hungary, leaving them bottom of the group.
For the other teams representing the UK, Northern Ireland were drawn into Group A with the winner of Germany vs Italy, Slovakia and Luxembourg.
Wales will play Belgium, North Macedonia and Kazakhstan in Group J.
In Group K, England drew Serbia, Albania and Latvia.