You must hold a security clearance in order to be granted a licence to handle explosives. A security clearance does not authorise you to obtain, possess, transport, use or otherwise handle explosives, you will need to apply for a separate licence. The clearance is a precondition for all explosives licences except the fireworks (single use) licence.
You will also require this clearance if you are employed or contracted to work under the direction or control of another person who holds an explosive licence. However, you will not require this clearance if you are working under supervision or working in a supervised area.