Help revolutionary over variable period in US (8)
I believe the answer is:
dystopia
'help revolutionary over variable period in us' is the definition.
I can't judge whether this definition defines the answer.
'help revolutionary over variable period in us' is the wordplay.
'help' becomes 'aid' (synonyms).
'revolutionary' says the letters should be written backwards.
'over' indicates putting letters inside.
'variable' becomes 'y' (y may represent a variable in algebra).
'period in us' becomes 'stop' (full stops are called periods in US English).
'aid' backwards is 'dia'.
'y'+'stop'='ystop'
'dia' placed around 'ystop' is 'DYSTOPIA'.
(Other definitions for dystopia that I've seen before include "where everything's bad" , "Imaginary society in which everything is bad" , "Imaginary place of maximum badness" , "worst possible place?" , "Undesirable place" .)