Socialist, without ceremony, rejected left (7)
I believe the answer is:
retired
'left' is the definition.
(I've seen this before)
'socialist without ceremony rejected' is the wordplay.
'socialist' becomes 'red' (red is a kind of socialist**).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'ceremony' becomes 'rite' (rite is a kind of ceremony).
'rejected' shows that the letters should be reversed in order.
'rite' backwards is 'etir'.
'red' enclosing 'etir' is 'RETIRED'.
(Other definitions for retired that I've seen before include "Withdrew from active participation" , "retreated" , "Ceased working" , "Stopped working" , "went back" .)