Rose suddenly developed petal (5)
I believe the answer is:
leapt
'rose suddenly' is the definition.
(to leap up is to rise suddenly)
'developed petal' is the wordplay.
'developed' is an anagram indicator.
'petal' with letters rearranged gives 'LEAPT'.
(Other definitions for leapt that I've seen before include "gone up dramatically" , "Jumped, sprang" , "Jumped a long way" , "rose fast" , "Made spring" .)