The term 'impish sort' is a phrase used to describe someone who is mischievous and playful. This term can be broken down into three crossword solutions: ELF (3 letters), RASCAL (6 letters), and SCAMP (5 letters). An ELF is a mythical creature often associated with mischief and pranks. A RASCAL is a person who behaves in a mischievous or naughty way. Finally, a SCAMP is a person who is mischievous and playful. All three words are used to describe someone who is impish and mischievous.