Assuming that the host is a windows based environment and the guest is s qemu based linux terminal only environment e.g ubuntu server without x11, then there are currently no features targeted specifically at exposing a character device in the terminal that one can redirect text to and from the host's clipboard. e.g.
1. from host -> guest (via spice clipboard)
host: copy from cheetsheet to clipboard
guest shell: dev/cb > <command> # redirect from clipboard device to standard out
2. from guest -> host (via spice clipboard)
guest: <command> > dev/cb # redirect standard out to the clipboard device
a. graphical paste menu item in some application
b. dev/cb > command # redirect from spice cb device on host to another command