Answer: knowitall

AnswerCrossword Clue
KNOWITALLWisenheimer
KNOWITALLSmart aleck
KNOWITALLAdvice ignorer
KNOWITALLWould-be expert
KNOWITALLSmarty-pants
KNOWITALLSmart aleck, say
KNOWITALLAdvice-disdaining sort
KNOWITALLOne needing no advice