Wiktionary
clay up
vb. To add clay to.
Usage examples of "clay up".
The Fox brought the lump of clay up to it with more than a little trepidation: if Geroge chose to bite down now, he'd spend the rest of his days one-handed.
Her conscience persisted as she rolled the sheet of clay up into a cylinder and flattened the cylinder into a sphere.
I could see incense burning in a far corner, but it hadn't done any good yet, because the smell of dead mouse struck me with as much force as if someone had stuck clay up my nose.