Socialist up for election hopelessly outperformed (4,8)
I believe the answer is:
left standing
'hopelessly outperformed' is the definition.
(to leave someone standing is to outperform them)
'socialist up for election' is the wordplay.
'socialist' becomes 'left' (associated in meaning).
'up for election' becomes 'standing' (standing for election).
'left'+'standing'='LEFT STANDING'
(Other definitions for left standing that I've seen before include "being too far behind" , "Abandoned candidature" .)