... sounds a little offish... I regret, but can a green card holder be considered for a local government job or federal govt job?. and if so ,some agencies call for some stringent security clearance,(I understand there are various levels here).. any luck on permanent residents with no criminal record of any sort?. or this is the preserve of US citizens only as some of these job adverts would put it by way of media?

There are some limitations in some higher level government positions, that require US citizenship, but the vast majority of government positions are open to LPR's. After all an LPR is a US national. Go for it!