This controls the current changeover (6)
I believe the answer is:
switch
This might be a double definition.
'this controls' is the first definition.
The definition suggests a singular noun which matches the answer.
'current changeover' is the second definition.
The answer and definition can be both related to natural events as well as being singular nouns.
Maybe there's an association between them I don't understand?
'the' is the link.
Can you help me to learn more?
(Other definitions for switch that I've seen before include "Change, substitute" , "Control for making or breaking connections" , "Change; hair-piece" , "Sudden change; a rod" , "Cane to control the light" .)