Bit of Roman arch is made to show radical concept (9)
I believe the answer is:
anarchism
'radical concept' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'bit of roman arch is made to' is the wordplay.
'bit of' indicates a hidden word.
'ANARCHISM' can be found hidden inside 'roman arch is made to'.
'show' acts as a link.
Can you help me to learn more?
(Other definitions for anarchism that I've seen before include "anti-government doctrine" , "Man's chair (anag.)" , "Anti-government ideology" , "Bakunin advocated it" , "lawless attitude" .)