ItsLeffdePeff
NOTE: a clean install will wipe the entire contents of your drive and you will lose everything not backed up.
My recommendation is always to back up your data before any OS installation. It is possible to shrink your Windows partition, enlarge the Windows ESP (if you are on a UEFI device), and then install Solus in a dual-booting configuration. You will still have access to Windows and all of your files from Solus. If you want to get rid Windows completely, you will need to copy all of the files that you want to keep to an external drive or back them up with a cloud service before doing a clean install of Solus.