A new CLSP with channel clearance (CLSP/CC) is proposed for obtaining better network performances in spread slotted ALOHA networks. This protocol can decrease wasteful channel usage by prohibiting continuous transmissions of packets already destroyed in previous slot, with little added network complexities. To validate the performance improvements of our protocol, both simulation and analysis are considered. As a result, the network using the proposed CLSP/CC is superior to that with CLSP, and also to the conventional one, especially when the system capacity is half of the offered load, and improves as the threshold for CLSP increases to network capacity.