Model initiated by party of socialist economic radicals (5)
I believe the answer is:
poser
'model' is the definition.
(I know that model can be written as poser)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for poser that I've seen before include "Toughie" , "This person's affected" , "Difficult problem" , "Spore raises a difficult question" , "Hard question" .)