Leader, a swine defended by right-wing tabloid (6)
I believe the answer is:
shogun
'leader' is the definition.
'a swine defended by right-wing tabloid' is the wordplay.
'a swine' becomes 'hog' (hog is a kind of swine).
'defended by' is an insertion indicator.
'right-wing tabloid' becomes 'sun' (The Sun, UK newspaper).
'hog' going into 'sun' is 'SHOGUN'.
(Other definitions for shogun that I've seen before include "Hereditary commander of feudal Japanese army" , "Hereditary Japanese military governor" , "So hung about with old Japanese army commander" , "Feudal Japanese leader" , "Foreign C-in-C" .)