Answer: witsend

AnswerCrossword Clue
WITSENDGiving-up point
WITSENDAt one's ....
WITSENDBad thing to be at
WITSENDBrain-racked state
WITSENDPoint of exasperation
WITSENDThrowing-in-the-towel point
WITSENDBoiling point?