If you've met or are going to meet the requirements in other aspects of the course then I'd recommend you focus most, if not all, of your attention on the subject you're struggling with. That's what I'm doing. I've pretty much met the requirements in all but one subject, so I've actually opted out of the final unit for one of the subjects because I have/will have enough credits from elsewhere allowing me to focus all my attention on the subject I need to get right.
Of course, there is a chance that they will be lenient, especially if you only miss out by a small margin. My advice is to cross that bridge if you come to it. Worrying about it can't be good, so I'd say you should focus on the course for the moment and hopefully you won't have to contemplate what you'll do if you just miss out on 60%.