Actor once in Parliament full of comic potential (8)
I believe the answer is:
dietrich
'actor' is the definition.
(I know that Dietrich is a actor)
'parliament full of comic potential' is the wordplay.
'parliament' becomes 'diet' (diet can mean a parliament in some countries).
'full of comic potential' becomes 'rich' (something 'a bit rich' is amusing or comical).
'diet'+'rich'='DIETRICH'
'once in' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for dietrich that I've seen before include "FILMSTAR" , "Marlene -, German actress" , "Old German film star had a cider hit" , "Marlene . . . . . . . ., late German star of stage and screen" , "Marlene ... old film star" .)