[Greg Jones]

I believe you are going to need two steps to accomplish this as you can only focus on folders or projects. You can click on Flag and change the view to flagged as you are doing now. Or you can create a 'Focus' context (one-time only), then set the task's context to 'Focus' and then select 'Show in Context mode'. Another option would be to drag the task to the top of list of tasks in the project, and select 'Next Action' from the View Bar.