Indisciplined (6)
I believe the answer is:
unruly
'indisciplined' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for unruly that I've seen before include "Disobedient and disruptive" , "Mutinous" , "Disorderly, hard to control" , "Rumbustious" , "Obstreperous" .)