Unfortunately no; you can't reserve a domain name. Website addresses are registered (licensed) to applicants on a "first-come, first- served" basis.
There is no provision for queuing of applications in the .AU registry, or most others.
If a domain name is already licensed, or if an application is pending for that website address, no further applications will be accepted for that name until the address is either revoked, registration expires or the pending application is declined for whatever reason.
If you're wanting to register a domain that is already taken by someone else, you can try using our domain name WHOIS feature, which will provide you with some contact information for the registrant. You will then need to negotiate directly with the registrant regarding the possible purchase and transfer of the name; with of course no guarantee of success.
If the domain name is registered but doesn't appear to be in use and the registrant is non-responsive to your communications, your only other option is to wait for the registration period to lapse and then to try getting it when it becomes available again - but bear in mind others may be waiting to register the website address too; particularly if it's a good one.
Given the time and uncertainty involved with acquiring someone else's already registered domain or waiting for a website address to expire; it's probably best to think up an alternative, then run a domain name search and register it quickly - before somebody else does!
Many people have been disappointed after having brainstormed good domains then delayed registering them, only to discover someone else has grabbed their favoured choices in the interim. Carpe Diem!
Pick up some tips for choosing good domains.
How to register a name: Enter your choice in the search tool and click 'GO'. If after the check the domain names search results show your choice is available, you will then have the option to proceed to purchase registration; which is a very quick and easy process - start a search and find your ideal website address now.