Citizen Kane's last word (7)
I believe the answer is:
rosebud
'citizen kane's last word' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rosebud that I've seen before include "Young flower (gathering recommended!)" , "J. Foster Kane's last word" , "one with potential to bloom" , "Young flower - Citizen Kane's last word" , "Partially-opened flower" .)