On Marshmallow, default Samsung Galaxy S5 keyboard I don't see a clipboard icon. However, following from a closed thread with advice that appears to now be out-of-date, to access the clipboard content try this:
- Copy some text into the clipboard (in case it's completely cleared, which would be rare, but some privacy/antivirus apps do this)
- Open any app where you enter text (phone text messages, Facebook, whatever), and click into the text entry window
- Manually long press that window
- You should get a two part pop-up icon with Paste and Clipboard options.
- Select Clipboard.
- From the resulting window you can select recent clipped/copied content or Delete All clip content
(You may also be able to access the clipboard when selecting text, but the dialog is not consistent between apps and type of text. When in selection of a piece of text, your Cut, Copy, Paste, Share, etc, dialog may have a three vertical dot "more" menu which takes you to the clipboard content.)
Hope this helps someone.