Throw into disorder (7)
'throw into disorder' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for derange that I've seen before include "Remove from order" , "Make mad" , "Put into confusion" , "Make insane" , "Unhinge" .)
(Other definitions for disrupt that I've seen before include "Interrupt and spoil" , "Disturb" , "Throw into disorder" , "Break up" .)