Sentence:  As a general rule, a stag treads more cleanly than a hind, his stride is longer, the slot itself being rounder and less elongated ; while a hind or young stag <WSD>understeps</WSD> frequently, leaving in consequence a more or less double track. 
Meaning of the word marked with <WSD> tags:  To have a gait in which the hind foot touches the ground behind the point where the front foot touches the ground.