Yes, you can run 5.1 from a 7.1 receiver. Connect only the front left, front right, center, surround left, and surround right speakers (and sub). Then, be sure you have a 5.1 speaker configuration selected in the receiver's setup menu.
Typically, this arrangement allows the use of the back/rear channels to be assigned to the Zone 2 system in an additional setup configuration.
Typically, this arrangement allows the use of the back/rear channels to be assigned to the Zone 2 system in an additional setup configuration.