Political theory of some zany brothers? (7)
I believe the answer is:
marxism
This clue might be a double definition.
'political theory' is the first definition.
(I've seen this before)
'of some zany brothers?' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for marxism that I've seen before include "Left-wing philosophy" , "Political doctrine" , "political philosophy?" , "Left-wing system" , "Communist belief" .)