Old revolutionary council about to replace five-year community (7)
I believe the answer is:
society
'community' is the definition.
(synonyms)
'old revolutionary council about to replace five-year' is the wordplay.
I cannot really see how this works, but
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is found within the answer.
'council' could be 'sc' (SC is an example) and 'sc' is found in the remaining letters.
'year' could be 'y' and 'y' is found in the answer.
This explanation may well be incorrect...
(Other definitions for society that I've seen before include "Fellowship, association" , "Fellowship; company" , "See 4" , "Fellowship, companionship" , "An organised community, may be high" .)