...
By default, Canvas will display the latest attempt in SpeedGrader. If needed, you can select (and download) the files from the earlier attempt(s) in Speedgrader by selecting the relevant attempt from the “Submission to view” dropdown.
Finally, you may want to support this Idea Conversation at Canvas Community to build this functionality (allow a specific student an extra attempt) in Canvas.
Alternative solutions
If the due date has passed, is to change the submission attempts, as above. However, as the due date has passed, you can assign the assignment only to the student(s) who need the extra attempt, without affecting those who already submitted on time.
You can create a separate assignment specifically for the student. Do note this will create a separate grade item in Gradebook.