In Mobile Ad Hoc Network (MANET), some routing protocols are proposed to hide the identity of node from outside entities that can observe data traffic which can be disastrous in military operations. However, existing protocols which provide full anonymity of source node, destination node and routes are vulnerable to malicious activités. The anonymous protocols hide the identity of the malicious node and enhance the possibility of Black Hole Attack. In order to provide anonymity without compromising the security, we have extended Anonymous Location Based Efficient Routing Protocol(ALERT) to make it secure. The secure version is named as Secure Anonymous Location Based Efficient Routing protocol (S-ALERT). S-ALERT uses Suspect Detection algorithm to choose the nodes in a route which provide unperceivable route. If there is existence of a Black Hole it actually sends a false RREP packet and advertises itself as the shortest route found. The proposed scheme avoid the black hole problem, and also prevent the network from further malicious behavior. Through simulation results it has been shown that proposed method can effectively detect and provide protection from black hole attack. S-ALERT routing efficiency is also better than existing protocols.