Singapore Expats

Hi, I am a Singapore citizen holding an Australian PR & currently living in Australia.
Just wondering whether it would be possible to extend/renew my Singapore passport since I am an NS Defaulter.

I know that I could try to renew my SG Passport in the Singaporean Embassy in Canberra, but wouldn't that also mean risking arrest/detain by the Singaporean Consulate?

No you can't as you need to to provide a valid Exit Permit or Notice of Exemption when applying when applying at High Commission Canberra

In fact, if you go into the Singapore Consulate, you are on Singapore soil and they may well detain you as you are a deserter and send you back to Singapore to do time.