### Clue: Girl gets punishment in the States for threatening behaviour (8)
### Answer: UGLINESS 
 ### Explanation: Definition: threatening behaviour
 { G(abbrev. for "girl") **plus**(gets) LINES(a form of punishment for schoolchildren) } **contained in**(in) US(abbrev. for the United States, of America).
Answer: Behaviour which could cause trouble is termed "ugly", as in "the discussion turned ugly".