Cause of malfunction of foreign government changing leader (7)
I believe the answer is:
gremlin
'cause of malfunction' is the definition.
(machine malfunctions might be blamed on gremlins)
I don't understand the remainder of the clue.
(Other definitions for gremlin that I've seen before include "Trouble-making imp" , "Imagined mischievous spirit" , "Mingler (anag.)" , "Cause of unexpected mechanical problem" , "Imp causing mechanical problems?" .)