OMG! My fondant rthatis covering the cake cracked near the bottom last night I have to deliver the cake in a few hours how can I fix it??????
I don't know if this will work for the type of crack you have, but once I had a crack in my fondant. I was able to color royal icing the same color, fill the crack and wipe away the excess. It didn't completely disappear, but it was close.
Hope this helps. Good luck!
The RI idea is a good one. Another option is if there are flowers or something like that on the cake you could cover the crack.