Actress and civil rights activist Ruby (3)
I believe the answer is:
dee
'actress and civil rights activist ruby' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dee that I've seen before include "Scots river" , "River at Chester" , "John ---, Elizabethan mage" , "Welsh/English river" , "Aberdeenshire river" .)