Govt. is a large concept and as a whole is the sum total of system of administration.One can't clean it whole unless to start from a key point.Politicians sit at top of system and flow of corruption flows downwards.So if politicians are compelled to leave corruption,whole system can be free of corruption.Being at top the politicians has in his hands the overall control over administrative set up and he thus manages to fulfill his goals by using administrative set up on his lines .If some members of administrative set up don't obey,they are liable to be punished and harassed in this form or the other.Therefore first of all the politicians of today must be compelled to step down and this can be done either by huge agitation or through polls.