Challenged socialist attorney first (5)
I believe the answer is:
dared
'challenged' is the definition.
(daring is a kind of challenging)
'socialist attorney first' is the wordplay.
'socialist' becomes 'red' (red can informally mean a socialist).
'attorney' becomes 'DA' (District Attorney).
'first' says to put letters next to each other.
'red' put after 'da' is 'DARED'.
(Other definitions for dared that I've seen before include "Took a risk" , "Risked" , "Had the nerve to" , "Was brave enough" , "Acted with courage - or dread?" .)