Is it ensure, insure, or assure?
"worked up to too high a pitch," 1825, literally "over-worked," from over- + wrought. Earlier it meant "exhausted by work" (1660s) as a literal past participle of overwork.
"to cause to work too hard," 1520s, from over- + work (v.). Old English oferwyrcan meant "to work all over," i.e. "to decorate the whole surface of." Related: Overworked; overworking.
"work beyond a person's strength," 1819; see overwork (v.). Old English oferweorc meant "a superstructure, sarcophagus, tomb."