expression, godan verb (-u)
even a clever woman is bound to mess up; a clever woman fails to sell a cow
Proverb warning that overconfidence or cleverness can lead to failure, specifically applied to women in a traditional context. The literal meaning is 'a clever woman fails to sell a cow'. Modern usage is rare and may be considered sexist.
The proverb 'onna sakashikute ushi uri sokonau' means that even a woman who thinks she is clever can sometimes fail.