Abrupt transitions (5)
I believe the answer is:
leaps
'abrupt transitions' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for leaps that I've seen before include "Jumps or springs suddenly" , "Pales in vaults" , "Pales (anag.)" , "Jumps or bounds" , "Makes fast progress - by . . . . . and bounds" .)