Leftist hurting inside came to (7)
I believe the answer is:
reached
'came to' is the definition.
(to come to is to reach or arrive at)
'leftist hurting inside' is the wordplay.
'leftist' becomes 'red' (red can informally mean communist).
'hurting' becomes 'ache' (ache is a kind of hurting).
'inside' indicates putting letters inside.
'red' enclosing 'ache' is 'REACHED'.
(Other definitions for reached that I've seen before include "Came to (a place)" , "Attained" , "Stretched or arrived" , "Cad here (anag.)" .)