Roller coaster or carousel (4)
I believe the answer is:
ride
'roller coaster or carousel' is the definition.
(I know that big dipper is a type of ride)
This is all the clue.
(Other definitions for ride that I've seen before include "badger" , "Be transported" , "spin > lift > pedal" , "Go by bicycle" , "Travel on the back of animal" .)