Hindered one politician with a terrible deed (7)
I believe the answer is:
impeded
'hindered' is the definition.
('impede' can be a synonym of 'hinder')
'one politician with a terrible deed' is the wordplay.
'one' becomes 'i' (Roman numeral).
'politician' becomes 'MP' (Member of Parliament).
'with' means one lot of letters go next to another.
'a terrible' indicates an anagram.
'deed' with letters rearranged gives 'eded'.
'i'+'mp'+'eded'='IMPEDED'
(Other definitions for impeded that I've seen before include "Obstructed" , "Held up" , "Hindered, slowed down" , "Got in the way of" , "Hindered progress" .)