Celtic striker Leigh Griffiths and Norwich City defender Grant Hanley have been recalled for Scotland's crucial Euro 2020 play-off with Serbia.
Aberdeen defender Andrew Considine has earned a return after performing well as a late call-up in wins against the Czech Republic and Slovakia last month.
As expected, Craig Gordon replaces Robby McCrorie as one of three keepers.
Scotland face Serbia in Belgrade on 12 November aiming to qualify for Euro 2020 next summer.
It is a chance for the men's national side to end what would be a 23-year wait for an appearance at a major finals.
They then take on Slovakia and Israel away from home in Nations League Group B3, which they currently lead.
Hibernian defender Ryan Porteous, Sheffield United's John Fleck (injury), and McCrorie are those to drop out from the initial squad announced for last month's internationals when Scotland extended their unbeaten run to eight matches.
Griffiths, 30, last played for Scotland two years ago in a Nations League win against Albania, having battled injury and personal problems intermittently since.
However, he has returned to the Celtic team and netted against Aberdeen and St Johnstone in recent weeks.
"Leigh has always been a goalscorer," Clarke said. "He's a dangerous player in the opposition's 18-yard box. Sometimes off the bench you need a goal, and with Leigh in the squad he can give you that option.
"I think he has to be 100% when he goes to the pitch," Clarke replied when asked if Griffiths can make an impact even if not fully fit.
"Whether he goes to the pitch for 97 minutes, 120 minutes or 20 minutes, he has to be 100%.
Norwich captain Hanley, 28, was an ever present under former head coach Gordon Strachan, and makes his return having last featured in a friendly against Costa Rice in March 2018.
His return from a hamstring injury has come during a five-match unbeaten run for the Canaries.
"He's had a tough time with injury," Clarke said of Hanley.
"He plays week in, week out when he's fit for Norwich. He's got plenty of international experience and I was surprised when I checked his age that he's only 28, he's got many good years ahead of him."
Goalkeepers: Marshall (Derby County); McLaughlin (Rangers); Gordon (Hearts)
Defenders: Considine (Aberdeen); Gallagher (Motherwell); McKenna (Nottingham Forest); Cooper (Leeds); O'Donnell (Motherwell); Palmer (Sheffield Wed); Robertson (Liverpool); Tierney (Arsenal); Taylor (Celtic); Hanley (Norwich City)
Midfielders: McTominay (Manchester United); Christie (Celtic); McGregor (Celtic); Armstrong (Southampton); Jack (Rangers); McGinn (Aston Villa); Kenny McLean (Norwich City)
Forwards: Dykes (QPR); Fraser (Newcastle); Burke (Sheffield United); McBurnie (Sheffield United); Griffiths (Celtic); Paterson (Sheffield Wed); Shankland (Dundee United)
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