Johnson is in doubt for Australia's key World Twenty20 Super Eights match against India with an elbow infection.
"Mitch is a huge part of our team with both bat and ball, hopefully he is fit." Clarke told cricinfo.
Australia are through to the second phase of the tournament following a comfortable win against world champions Pakistan in St Lucia and survived an early scare to beat Bangladesh in Barbados.
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Clarke was licking his lips ahead of the opportunity to unleash his quick bowlers on India.
“These conditions are really going to help our fast bowlers.
There was a lot of pace and bounce in that wicket," the skipper said.
Clarke grinned when asked if his pace men would deliver some chin music to the Indian batsmen.
“I don't think I'll have too much of a say. Our fast bowlers will bowl as much short stuff as they like," he said.
"We cop it in the nets so we'll definitely see it in the game. We've got some pace up our sleeve and I'm sure in these conditions we'll be able to use it."
Indian coach Gary Kirsten says it's too simplistic to suggest Friday's clash between Australia and India at Kensington Oval in Barbados is going to come down to Australia's pace barrage versus India's spin wizardry.
"The Australian pace men will play a role as will the Indian spinners. But I think there's more to it than that, especially in the 20-over format. Kirsten told AAP on Wednesday.
Kirsten also hit out at claims that India were clear favourites after Australia wasn't seeded for tournament.
"They are a good side; they have quality in their side as does India.”
"Since when do you under-rate an Australian team? An Australian team is always a strong team,"
India cruised to the Super Eights stage from wins over Afghanistan and South Africa.
