Susan cries out, dropping end of blue flower (9)
I believe the answer is:
narcissus
'flower' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
(Other definitions for narcissus that I've seen before include "Reflective chap" , "In Greek myth, youth in love with his reflection" , "Flower; Gk. youth in love with reflection" , "Beautiful fellow" , "Legendary youth who fell in love with his own reflection" .)