I score overall 6.5 in ielts bhut in one module it is 5.5 can I apply for masters in australia?

The IELTS score requirement varies across courses, schools and countries thus you need to check the requirement based on the course that you wish to pursue as well as your school and country preferences. 

On an average, 7.0 band is a safe score which is accepted by a majority of schools abroad. 

On the other hand, some schools do not even ask for an IELTS score as a mandatory requirement. 

So the wise approach here would be to check the options available for your preferred course and schools. 

Let me know about the course you wish to pursue and maybe then I can narrow down some options for you.