I'm confused, is the issue that you have a lower result in a single module, or that you have a low result overall?
Having a single module being a lower grade but still meeting the overall average requirementa nd the requirement for the thesis/dissertation result I don't think would necessarily be a problem (although if the module is in an area directly relevant to your DPhil project proposal that might be an issue...?).
If the issue is that you would need to currently apply with the "weaker" achieved grades, bear in mind usually individual module results are subject to exam boards in the summer so your overall results are still pending. Equally I gather it's not unusual for students to have to apply to PhD projects in a "gap year" after a 1 year masters course as I understand, simply due to the timelines involved - and so even if you aren't successful this year, that may simply reflect the fact having the masters in progress rather than in hand is the issue.
I'd probably also suggest discussing with your personal tutor/dissertation supervisor to make clear your intentions to apply to a PhD and discuss the best strategy to do so in this case.