Unnerves (4)
(Other definitions for alarms that I've seen before include "Warning clocks that wake us up" , "Scares or startles" , "Warnings of danger" , "Warning signals" , "Frightens, makes afraid" .)
(Other definitions for jars that I've seen before include "Grates" , "Wide-mouthed containers" , "Jam pots" , "Vessels with a wide mouths" .)