Clark has been out of action since December with an elbow injury
Stuart Clark has been called into the Australia squad for the remainder of the South Africa tour plus the upcoming series against Pakistan in the UAE.
The 33-year-old seamer will replace Brett Geeves, who is flying home after suffering a broken left foot.
But Clark's call-up is a blow to English county side Kent, for whom he was due to make his debut on 21 April.
The series against Pakistan does not end until 7 May and Kent are now looking for a new overseas signing.
Chief executive Paul Millman told BBC Sport: "We are delighted for Stuart that he has been called up by Australia but it obviously it means he'll be unable to fulful his contract with us. It's just a matter of it not fitting in with his timetable."
Clark's return to action in South Africa follows a lengthy absence from the game because of en elbow injury.
He is due to join the squad on Sunday but is unlikely to play in the game in Port Elizabeth the following day. He could, however, come into consideration for the fifth and final match in Johannesburg next Friday.
Australia will then head to the UAE where they will meet Pakistan in five one-dayers and a Twenty20 international in the space of 15 days.
It means Clark would have been unable to make his debut for Kent until their Friends Provident Trophy game against Warwickshire on 10 May.
And he would have only been unable to play more than two Championship matches for the club before he joins up with Australia again for this summer's Ashes series, assuming he is selected.
Australia begin their tour to England with a three-day match against Sussex at Hove, starting on 24 June.
Millman added: "We have a good relationship with Stuart and there is still the possiibility he may be able to play for us sometime in the future, but as from now, we are actively looking around at other options.
"Because the news came through so quickly we have been unable to arrange anything straight away, but we are now looking around at alternatives for this season."