One flower appeared (5)
I believe the answer is:
arose
'appeared' is the definition.
(I've seen this before)
'one flower' is the wordplay.
'one' becomes 'a'.
'flower' becomes 'rose' (I've seen this before).
'a'+'rose'='AROSE'
(Other definitions for arose that I've seen before include "Sprang up" , "''. ... by any other name would smell as sweet'' (Romeo and Juliet)" , "Emerged from" , "Happened" , "Got out of bed" .)