Frequent nodal movements in MANET make path setup and clustering algorithm a challenging task. We provide a new mobile estimation algorithm in MANET. We develop a simple heuristic mechanism to derive the mobility index, used for characterizing its instantaneous nodal mobility. Simulation results reveal that the estimated mobility index of a node follows a linear relation with its own real speed. Next, we apply the mobility index to derive the mobile awareness based cluster election scheme and path setup mechanism. Performance results have shown that our mechanism outperfom other mechanisms in various environments.