Fly into a rage and go off (4,2)
I believe the answer is:
blow up
This clue is a double definition.
'fly into a rage' is the first definition.
(both can mean to become very angry)
'go off' is the second definition.
(I've seen this before)
'and' is the link.
(Other definitions for blow up that I've seen before include "apply inflation" , "Destroy with explosion" , "Enlarge - wreck - inflate" , "reduce to smithereens" , "Burst" .)