A certificate of clearance is needed when applying for visas to other countries (especially for long term stays). Information can easily be found on the Singapore Police website.
BUT! An important note for non-Singaporeans:
And a note for everyone:
Do not trust the hotline people! Get a second opinion! Before going, we called and asked if a photocopy of our passport is sufficient because R’s passport was at the Philippine embassy.. we were told it was fine, a photocopy is the only thing needed. So that’s what we brought: just a photocopy of his passport details page.
Turns out he was wrong.
For PRs and foreigners, you will need to present proof of your length of stay here: immigration stamp of your first entry on your passport, employment contracts, copies of your old employment pass. Any kind of proof will do as long as you can show that you have been in Singapore for as long as you say you have.
Once you have everything in order, the process is quite fast. You pay the COC fee and a few minutes later your name will be called for fingerprinting on a gigantic fingerprint computer. And this is not a joke: moisturize your hands! Or else your prints won’t be captured.
Also, try to get there early, the queue can be quite long and seats can be scarce at the waiting area.