Neither Scott McTominay nor Kieran Tierney have travelled with Scotland due to slight injuries, with Clarke saying both carried knocks into the camp.
The Scotland head coach also revealed he has decided who will start in goal, after Cieran Slicker endured a tough debut against Iceland when he replaced Angus Gunn after just a few minutes, with Robby McCrorie also injured in the warm up.
Ross Doohan, who has just left Aberdeen, and 18-year-old Bournemouth goalkeeper Callan McKenna have been called up as replacements for Gunn and McCrorie.
“Cieran is a good goalkeeper,” added Clarke, of the 22-year-old Ipswich player.
“He trains well, works well in the camp. He’s had an unfortunate night and he’ll bounce back from it.
“He knows he needs to play more games regularly but he’s got a big future in front of him.”
Clarke also added the team will be freshened up “a little bit more than I’d normally do”.
This is Scotland’s final game before they start World Cup qualification in September, with Denmark, Belarus, and Greece making up their group.
