Yes, it is possible to offer a weekly or special tour/class/workshop or a course as private on a specific day (and viceversa). This means that you will only accept one booking on a specific day.
1. Go to your Calendar
2. Click on the tour/class/workshop to open it 
3. Use the Private drop-down arrow, from the scroll down menu, select:
- yes if the tour/class/game is private on that date. This means that you will accept one booking for that tour/class/game, regardless of the number of participants
- No if the tour/class/game is not private on that date. This means that you will accept multiple bookings for that tour/class/workshop
4. Save