One daughter has said that Organic Chemistry was the most difficult B- that she ever had in her life. She is currently studying for a DVM at a highly ranked university (admission being about as difficult as an MD) after having four acceptances with only one rejection. I also know a nurse practitioner for whom Organic Chemistry was the only C that they ever had in their life.
I think that this is okay. You will need a few A’s in other courses to make up for a B, but I suspect that you will be able to do this.
One thing that might be in your favor here: Premed classes are intentionally quite difficult. There will be very few (if any) students who have nothing but A’s throughout their premed classes. This means that you can get away with a small number of B’s.
Also of course your experience in a medical environment and your references will matter quite a bit, as will your MCAT scores.