Socialist checked out (4)
I believe the answer is:
left
I believe this clue is a double definition.
'socialist' is the first definition.
('left' is associated in meaning with 'socialist')
'checked out' is the second definition.
(Other definitions for left that I've seen before include "Communist?" , "Withdrew - Labour" , "The sinister side" , "Departed, went away" , "Socialist direction" .)