Goalkeeper Foster has been sidelined since suffering a stress fracture in his foot in August and he will miss England's games against Germany and Chile later this month.
In his absence, John Ruddy and Fraser Forster could be given the opportunity to press their claims to be current first choice Joe Hart's understudy.
Foster featured against the Republic of Ireland in May after ending his international exile and he played under England coach Roy Hodgson at West Brom.
Clarke, who succeeded Hodgson at The Hawthorns, does not want to rush Foster back, but suggests the 30-year-old will have plenty of time to state his case for inclusion in the England squad travelling to Brazil next summer.
"The key thing is that Roy knows him, he had him in his last year at the club," said Clarke. "He understands Ben as a person and a player, which is good for both of them.
"He won't be ready mid-November, but he will be ready for the one in March. First and foremost, he has to get fit and get over a serious injury.
"We will all give him a little bit of time and space, and let him get back on the training pitch. When he is back on the training pitch and fully fit, then we can start to have this conversation that people want to have about him getting back into my team and the England team.
"He is weight-bearing again on the foot and things are progressing well. He is starting to see a bit of light at the end of the tunnel, which is important for him as well."