clench vs prehend

clench is a noun but prehend is not a noun.

Word	Noun	Adjective	Verb	Adverb
clench	Yes	No	Yes	No
prehend	No	No	Yes	No

As verbs, prehend is a hypernym of clench; that is, prehend is a word with a broader meaning than clench:

Other hypernyms of clench include clutch, seize, take hold, take hold of.

clench (noun)	prehend (noun)
the act of grasping
a small slip noose made with seizing

clench (verb)	prehend (verb)
hold in a tight grasp	take into your hands deliberately
squeeze together tightly