Behaves badly (4,2)
'behaves badly' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Another definition for acts out that I've seen is " Performs in a play".)
'behaves badly' is the definition.
(acting up is a kind of behaving badly)
This is the entire clue.
(Other definitions for acts up that I've seen before include "Behaves badly (colloq.)" , "Fails to function properly or behaves badly" , "Misbehaves badly" , "Malfunctions" , "Causes trouble or misbehaves" .)