to be too intelligent or know too much about sth to be tricked by other people :
She's nobody's fool when it comes to dealing with difficult patients.
to be too intelligent or know too much about sth to be tricked by other people :
She's nobody's fool when it comes to dealing with difficult patients.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005