Usually the cancellation policy is at least 24 hrs in advance, so in your friend's case, makes not diff. if he called 5 hrs or 1 hr before the appointment.
However, if he has a valid reason (eg. emergency, hospital..), the clinic might accept that.
I made an appointment in the hospital. And I canceled it 1 or 2 hrs before the appointment due to I got a fever. There was no penalty. As marklin said, if the excuse is reasonable, the clinic might accept it.
Tell them that you are sorry and want to make another appointment in the near future. Also tell them that you wish not to pay the fine if you make another appointment. Good luck.