Go for a revolutionary number one sausage (9)
I believe the answer is:
pepperoni
'sausage' is the definition.
(I know that pepperoni is a type of sausage)
'go for a revolutionary number one' is the wordplay.
'go' becomes 'pep' (both can mean energy or vitality).
'for a' becomes 'per' ('per' can mean 'for each' person or 'for a' person).
'revolutionary' shows that the letters should be reversed in order (letters revolve around).
'number' becomes 'no' (abbreviation).
'one' becomes 'i' (Roman numeral).
'no' back-to-front is 'on'.
'pep'+'per'+'on'+'i'='PEPPERONI'
(Other definitions for pepperoni that I've seen before include "what may be called a banger" , "Highly-seasoned sausage" , "spicy stuff" , "Spicy snacks" , "Spicy Italian sausage" .)