Feet-clay is a colloquial term that is often used to describe someone who is slow or unproductive. There are various synonyms that can be used in place of this phrase. Some of the popular choices are sluggish, lethargic, unenergetic, and idle. These words all indicate a lack of movement or activity. Another synonym for feet-clay is torpid, which suggests a state of inactivity or slowness due to laziness or inertia. Alternatively, one could use the word indolent which means lazy or apathetic. Whatever synonym chosen, it should accurately convey the intended meaning and help the reader understand the context of the situation.