Robertson has played in five of Clarke's six matches in charge of Scotland

Assistant head coach Alex Dyer says the latest four call-offs from the Scotland squad, including captain Andy Robertson, are all "genuinely injured".
Arsenal asked for Kieran Tierney to be excused from the original squad despite the left-back now playing regularly for his club following hip surgery.
Scott McTominay, Ryan Fraser and Liam Cooper have now all also pulled out for the forthcoming Euro 2020 qualifiers.
"If a player is injured, we can't do anything about it," Dyer said.
"All the ones that have pulled out this time are genuinely injured. It's not like they wanted to be pulled out or didn't want to come."
Celtic winger Lewis Morgan, Derby County midfielder Graeme Shinnie and Hibernian central defender Ryan Porteous have been called up for the matches against Cyprus and Kazakhstan in place of Liverpool left-back Robertson, Manchester United midfielder McTominay, Bournemouth winger Fraser and Leeds United center-half Liam Cooper.