Of course you can. You may be behind in some topics, but providing you work really hard you can end up with an A*. By working hard I mean by getting the course textbook, going through every single example and understanding them fully, as well as doing every single question in the book and getting most of them right. While this may seem overkill to some, it will improve your "mathematical fluency" to such a point, where they can't throw a question at you that you can't solve.
Hard work is directly proportional to an A*.