Despite the fact that it remains a piece of the American vernacular, I don’t know how important it is that student know this word. Nonetheless, here is a context clues worksheet on the noun henchman. I will say this, as I consider this document: when I taught in New York City, the vanishingly few upperclassmen I taught, almost to a one, tended to refer to their youngest peers in the institution as “freshmans.” This worksheet might be best, I suppose, paired with the plural “henchmen” somehow to make sure students understand that the noun “man” declines, in the plural, to “men,” not matter where in a word it is found.
If you find typos in this document, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.