Source : Webster's Revised Unabridged Dictionary (1913)

Clench \Clench\, n. & v. t.
   See {Clinch}.

Source : WordNet®

clench
     n 1: a small slip noose made with seizing [syn: {clinch}]
     2: the act of grasping; "he released his clasp on my arm"; "he
        has a strong grip for an old man"; "she kept a firm hold
        on the railing" [syn: {clasp}, {clutch}, {clutches}, {grasp},
         {grip}, {hold}]
     v 1: hold in a tight grasp; "clench a steering wheel" [syn: {clinch}]
     2: squeeze together tightly; "clench one's jaw"