Actress slim and well-to-do (8)
I believe the answer is:
dietrich
'actress' is the definition.
(Marlene Dietrich, 1901-1992)
'slim and well-to-do' is the wordplay.
'slim' becomes 'diet' (diet can mean to slim down).
'and' says to put letters next to each other.
'well-to-do' becomes 'rich' (similar in meaning).
'diet'+'rich'='DIETRICH'
(Other definitions for dietrich that I've seen before include "Marlene ..., German-born film star" , "Former actress" , "FILMSTAR" , "Marlene . . . . . . . . was a famous film star" , "Old German film star had a cider hit" .)