Came to communist with internal pain (7)
I believe the answer is:
reached
'came to' is the definition.
(I've seen this before)
'communist with internal pain' is the wordplay.
'communist' becomes 'red' (red can informally mean communist).
'with' means one lot of letters goes inside another.
'internal pain' becomes 'ache' (ache is a kind of pain. I am not sure about the 'internal' bit.).
'red' placed around 'ache' is 'REACHED'.
Can you help me to learn more?
(Other definitions for reached that I've seen before include "Attained" , "Came to (a place)" , "Cad here (anag.)" , "Stretched or arrived" .)