Unruly tyke (4)
I believe the answer is:
brat
'unruly tyke' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for brat that I've seen before include "Ill-mannered child" , "Irritating youngster" , "Horrible child" , "Little terror" , "Bad child - pack member!" .)