Answer: catchon

AnswerCrossword Clue
CATCHONBecome popular
CATCHONGain in popularity
CATCHONUnderstand finally
CATCHONUnderstand
CATCHONUnderstand.
CATCHONBecome popular.
CATCHONGet the idea
CATCHONGrasp, as a joke
CATCHONGet the picture
CATCHONGrow in popularity
CATCHONTake root