Jack was a surprise inclusion in Clarke’s 23-man list considering he has not featured for the Ibrox side since limping off with a calf injury during the Champions League defeat to Liverpool on October 12.
The 30-year-old was not expected to return until after the World Cup but the Scotland boss revealed he has been in regular contact with Rangers and has been told that Jack could return for the match against St Mirren this weekend.
Clarke said: "We've have consistent dialogue with Rangers and his injury has improved. I like Ryan as a player. He probably won't play against Hearts tonight [Wednesday] but he could be back at the weekend."
Jack has 13 caps and started the most recent Scotland fixture – the goalless draw away to Ukraine in Poland in September – which clinched Nations League promotion.