Can I clean-install iOS 11 on my iPhone 7? My iPhone 7 is too buggy since I upgraded it to the iOS 11 beta. Now the iOS 11 had finally been released for a while, but my iPhone, even after upgraded to the official release, still too buggy (while using an app, the screen suddently got freezed and it is not responsive for a few minutes; an app didn't launch sometimes and crash immediately; etc...).

I already cleaned all my data and settings, and restored it from my backup, but it didn't resolve the issue.

So I would rather like to clean-install it. Is it possible to do that in iPhone?
Yes. Download the latest .ipsw file for your device. I get my stuff from Redmond Pie. I prefer clean installs as well. The .ipsw file is around 2-2.6 GB.