Click on the Safari menu at top left, choose Preferences from the dropdown menu. Note: Since macOS 13 Ventura, Preferences are called Settings Click the Advanced tab of the dialog that pops up. At bottom of dialog, select Show Develop menu in menu bar. Close the Preferences dialog Click the Develop menu at the top of the screen. Click Empty Caches from the dropdown menu.
Note: There are simpler ways to do this, but activating the Develop menu gives you easy access to this function whenever yu need it in future. Plus you get access to other useful developer features, such as the ability to switch off JavaScript.
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