Revolutionary attack knocking out one African town (5)
I believe the answer is:
lassa
'african town' is the definition.
(town in Nigeria)
'revolutionary attack knocking out one' is the wordplay.
'revolutionary attack knocking out' becomes 'lass' (I can't justify this - if you can you should give a lot more credence to this answer).
'one' becomes 'a'.
'lass'+'a'='LASSA'
(Other definitions for lassa that I've seen before include "-- Fever, acute viral disease" , "sort of fever" , "fever originating in 20 [NIGERIA]" .)