Stewart, Curtis and Gordon, 43, in Scotland World Cup squad
"From January onwards, he's had a rich vein of form where he's shown that he can score big goals in big games. "The Arsenal game in the cup, he shows he can have an impact in games of that level.
"From January onwards, he's had a rich vein of form where he's shown that he can score big goals in big games. "The Arsenal game in the cup, he shows he can have an impact in games of that level. "The World Cup will be a very high level as well.
He's shown that he can score from the bench. " Stewart has scored 11 goals in 33 Southampton games this season, including one in the Championship play-off semi-final win against Middlesbrough. Boro's Scottish forward Tommy Conway, 23, also featured in that semi-final but an injury sustained in the second leg rules him out of the World Cup.
"I spoke to Tommy," added Clarke. "Obviously, devastated with the injury. He had a great season with his club.
It's very disappointing for Tommy that he misses out. " The Scots face Haiti (14 June), Morocco (19 June) and Brazil (24 June) in Group C. The first two group games will take place in Massachusetts, with the final fixture in Miami.