Microsoft’s Office team announced Office.com Clip Art and image library has closed shop due to usage declining year-to-year as customers rely more on search engines. When customers searching for Online Pictures in Office desktop products worldwide will view and download royalty-free images curated through Bing Images.
Bing Image Search has higher quality images that are more up-to-date. Also, Bing will automatically apply copyright filter based on Creative Commons licensing system which allow you to use, share, or modify for either personal or commercial use (settings can be switched to Show all web results to view more images).
In programs like Word 2013, Outlook 2013 or PowerPoint 2013:
Click Insert > Online Pictures to use the Bing Image Search
In Office 2010 and Office 2007 programs:
go to Insert > Clip Art and search for pictures in the menu.
Refer to more info at Office Online [Where is the Clip Art site?]