clarion (n.)

"small, high-pitched trumpet," early 14c., from Old French clarion "(high-pitched) trumpet, bugle" and directly from Medieval Latin clarionem (nominative clario) "a trumpet," from Latin clarus "clear" (see clear (adj.)). Clarion call in the figurative sense "call to battle" is attested from 1838 (clarion's call is from 1807).