public OnPlayerConnect(playerid)
{ 
    new name[MAX_PLAYER_NAME];
    GetPlayerName(playerid, name, 24);
    if(strfind(name, "[sK]", true) != -1)
    {
        //if(PlayerInfo[playerid][ClanAccepted] == 1) Try to make a system to save your clan members instead of kicking them every time 
        {
            SendClientMessage(playerid, -1, "You are part of [sK] Community.");
        }
        else
        {
            SendClientMessage(playerid, -1, "[Error] - You are not allowed to use clan name [sK]");
            //Kick(playerid); or freeze him do what ever you want.
        }
    }
     return 1;
}