European region ousting leader accepts deed is cause of complaint (8)
I believe the answer is:
bacteria
'cause of complaint' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'european region ousting leader accepts deed' is the wordplay.
'european region' becomes 'iberia' (I've seen this before).
'ousting leader' means to remove the first letter (to oust is to remove).
'accepts' indicates putting letters inside.
'deed' becomes 'act' (an action).
'iberia' with its first letter taken away is 'beria'.
'beria' going around 'act' is 'BACTERIA'.
'is' is the link.
Can you help me to learn more?
(Other definitions for bacteria that I've seen before include "The organisms are in bait race, strangely" , "Infectious organisms" , "Germs or bugs" , "Single cell micro-organisms" , "These single-cell organisms are in bait race" .)