Fasted cardio in the mornings for an hour has always worked for me. Brisk walk at an incline on the treadmill. Nothing to strenuous.
Also eat very clean. Lots of greens and lean meat. And cut alcohol out. During some serious cutting i did, didn't drink for 3 months and managed to get into the single digits from 12/13ish %
If you are wanting more definition in your chest, arms and shoulders, and ate truly at 15% bf, cutting won't help you much there. You'll need to pack on some muscle.
Reference pic of bf %
