Credit is one of the biggest reasons people get denied a security clearance in the government, as there is worry one with poor finances/credit could become susceptible to blackmail from a foreign government/organization. This is a bigger deal in the IC than the FAA I would imagine though.
It's impossible for anyone here to say whether you will get a clearance or not with this issue. Just be completely upfront about it, show what you are doing to fix it, and the rest is then out of your hands. Good luck.