this is issue have been very controversial in the Public Sector.
Its like chicken and egg.
You cant get a job if you dont have security clearance.
You cant get a security clearance if you dont have 'that' job.
Security clearance are initiated by employers (usually Federal Government) who will 'sponsor'' you.
You need to be an Australian Citizen to apply for it and this is on a demand basis only. There should be an absolute reason before they can apply for one. (applying for a job or role is not a reason).
Unfortunate that this is one of the reason why its very difficult to find a job in the ACT But very fortunate for those who already has, they are very well in demand.