Slander repulsed a Russian assembly (4)
I believe the answer is:
duma
'russian assembly' is the definition.
(I've seen this in another clue)
'slander repulsed a' is the wordplay.
'slander' becomes 'mud' (as in to drag someone's name through the mud).
'repulsed' says the letters should be written in reverse.
'mud' written backwards gives 'dum'.
'dum'+'a'='DUMA'
(Other definitions for duma that I've seen before include "council" , "Russian elected parliament" , "Russian legislative assembly" , "Russian state assembly" .)