Creamy-white colour (5)
(Other definitions for ivory that I've seen before include "Key material" , "recluse's tower?" , "pasty" , "Elephant tusk material" , "Piano key" .)
'creamy-white colour' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for magnolia that I've seen before include "bush" , "Mississippi, the ___ State - tree or shrub" , "Tinted white colour" , "tree blossoms" , "Tree with solitary flowers" .)