That clenches.

1

1791.  E. Darwin, Bot. Gard., II. 80. And opes his clenching hands.

2

1833.  Mrs. Browning, Prometh. Bd., Poems 1850, I. 142. The clenching tooth.

3

1865.  Dickens, Mut. Fr., II. xi. The clenching palm of his left hand.

4