Rather small-minded Republican interrupts (6)
I believe the answer is:
pretty
'rather' is the definition.
(synonyms)
'small-minded republican interrupts' is the wordplay.
'small-minded' becomes 'petty' (synonyms).
'republican' becomes 'R' (abbreviation).
'interrupts' means one lot of letters goes inside another.
'petty' going around 'r' is 'PRETTY'.
(Other definitions for pretty that I've seen before include "Pleasing to look at" , "Fairly - good-looking" , "comely" , "pulchritudinous" , "Fairly; appealing" .)