clinker n.

"to ring, jingle, give forth a sharp, metallic sound," early 14c., echoic (compare Dutch klinken, Old High German klingan, German klingen); perhaps a weakened form of clank. Transitive sense, "cause to produce a sharp metallic sound" is from late 14c. Related: Clinked; clinking.

"to grasp firmly," c. 1300, from Old English (be)clencan "to hold fast, make cling," causative of clingan (see cling, and compare clinch); compare stench/stink. Meaning "to set firmly together" (of fists, teeth, etc.) is from 1747 (clinch in this sense is attested from 1630s). Figurative sense of "fix or secure by a final act" is from 1670s.  Related: Clenched; clenching.

1560s, "fix securely (a driven nail) by bending and beating it back," a variant of clench (q.v.). The sense of "settle decisively" is first recorded 1716, from the notion of "clinching" the point of a nail to keep it fast. Boxing sense is from 1860. Related: Clinched; clinching.