Dismissed if turning socialist (5)
I believe the answer is:
fired
'dismissed' is the definition.
('fire' can be a synonym of 'dismiss')
'if turning socialist' is the wordplay.
'turning' says the letters should be written in reverse.
'socialist' becomes 'red' (red can informally mean a socialist).
'if' backwards is 'fi'.
'fi'+'red'='FIRED'
(Other definitions for fired that I've seen before include "Aroused" , "Discharged" , "Dismissed or ignited" , "got rid of" , "Dismissed; set off" .)