Old city scouts regularly rebel (9)
I believe the answer is:
spartacus
'rebel' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see a link between them that I can't see?
'old city scouts regularly' is the wordplay.
'old city' becomes 'sparta' (I've seen this before).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'scouts' are 'cus'.
'sparta'+'cus'='SPARTACUS'
Can you help me to learn more?
(Other definitions for spartacus that I've seen before include "Thracian who led the 73 BC slave revolt against Rome" , "Rebellious Roman slave. d. c.71BC" , "Rebel Roman slave" , "Famous gladiator who led revolt against Rome" , "Roman revolutionary" .)