Blow a fuse (4,2)
'blow a fuse' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rage that I've seen before include "spread rapidly" , "Fury, passion" , "Speak with great anger" , "storm" , "Uncontrolled anger" .)
(Other definitions for lose it that I've seen before include "Snap" , "Suddenly go berserk" .)