Won't let you delete it? What sort of error(s) are you getting? If you look at the settings on the Safari.app bundle, select Safari and press Command-I (Get Info) and post a screen shot of the sharing and permissions section of the Get Info display.
You'll have to delete that bogus Safari.app (somehow), then empty the trash, and then reinstall the combo update. See if that clears this. Failing that, delete the bogus Safari, empty the trash, and download OS X 10.7.5 from the Mac App Store previous purchases — the entire distro, not the combo update — and reinstall it, or see if the recovery partition can restore the files.
If there aren't any current backups here, I'd suggest getting the backups going first, so that you have a path out if the disk goes walkabout or the upgrade fails. Then get ongoing backups configured and operating, as all storage and all computers and all disks can and will inevitably fail, and there are far more important files — and files that are far harder to recover than Safari — on your Mac.
If your Mac supports it — not all systems running 10.7.5 do — OS X 10.11 is the current release, and that'll load a current version of everything, including current Safari. Have a backup before you try that, though.