Abstract: The MANET faces critical issues due to the various attacks like wormhole, black hole, greyhole and even collaborative attacks. To overcome this issue, we propose to develop a detection scheme to detect and prevent collaborative attacks. Initially, clusters are formed with neighbourhood of nodes with a monitor node with all nodes at its 1 hop neighbours. This monitor node is chosen using an algorithm considering the willingness and trust value of a node. Then, we use ADCLU algorithm utilizing the monitor node to detect malicious nodes in a neighbourhood of nodes. Here, each pair of nodes may not be in radio range of each other but where there is a node among them which has all the other nodes in its 1 hop vicinity. The detection is based on voting from all other nodes about a certain message. The malicious node detected is isolated and further communication with this node is stopped.