Unexpected and inexplicable change (6)
I believe the answer is:
vagary
'unexpected and inexplicable change' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for vagary that I've seen before include "Unexpected and inexplicable change" , "Whim, caprice" , "Capricious idea for a gravy" , "Clip out, cut off" , "Erratic action" .)