Republican blocked payment for inflammatory poster (5)
I believe the answer is:
troll
'inflammatory poster' is the definition.
'troll' can be an answer for 'poster' (I have seen 'Provocative poster' mean 'troll' so perhaps 'poster' could also mean 'troll'). I am not certain of the 'inflammatory' bit.
'republican blocked payment' is the wordplay.
'republican' becomes 'r' (abbreviation).
'blocked' means one lot of letters goes inside another (to block can mean to box in or contain).
'payment' becomes 'toll' (I can't explain this - if you can you should give a lot more credence to this answer).
'r' inserted within 'toll' is 'TROLL'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for troll that I've seen before include "Internet provoker; ugly being" , "In Scandinavia, a mythical giant or dwarf" , "supposedly lives in a cave" , "Fish - cave-elf" , "Online annoyance" .)