You should look into this post: https://discuss.clearancejobsblog.com/t/alcohol-consumption/16
As for the alcohol part: I would say that it probably wouldn’t disqualify you from a clearance, but you can really improve your chances by seeking treatment (e.g. AA) and documenting it. Since you say that you have no trouble abstaining, then this should be a breeze.
However, I would put some caution to you about how this will impact your hiring timeline. I am going through this transition personally (graduate student to cleared contractor employee) and you have to understand that it, on average, takes a few months to go from ‘looking for a job’ to ‘hired, filling out SF-86’. If you could get an interim, then that would only take a month or three, and you could start work in a reasonable amount of time. Or you could do non-cleared work for a company/agency while waiting. But if you get yourself in a situation where you accept a ‘job offer conditional on clearance’, then you could be in for a long wait. Your file isn’t exactly squeaky-clean, and it’s very likely that you will have to list some foreign friends (it just comes as a part of going to grad school). So odds are pretty well against an interim. If you need to wait for the full clearance, then you might not be able to start work for 6-9 months after accepting the job offer.
If you can stomach that risk, then go for it. But I would really caution against accepting a conditional job offer unless you can manage that timeline.