Revolutionary seal around part of London (7)
I believe the answer is:
chelsea
'part of london' is the definition.
'revolutionary seal around' is the wordplay.
'revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary).
'around' indicates anagramming the letters.
'seal' with letters rearranged gives 'lsea'.
'che'+'lsea'='CHELSEA'
(Other definitions for chelsea that I've seen before include "Side" , "West London area" , "The Blues of Stamford Bridge" , "Hillary Clinton's daughter" , "place of buns" .)