Turn over part of phenomenal plant (7)
I believe the answer is:
anemone
'plant' is the definition.
The answer is an example.
'turn over part of phenomenal' is the wordplay.
'turn over' shows that the letters should be reversed in order.
'part of' indicates the answer is hidden within the clue.
'enomena' is hidden within 'phenomenal'.
'enomena' reversed gives 'ANEMONE'.
(Other definitions for anemone that I've seen before include "Bright flower or sea plant" , "Tentacled sea dweller, flower" , "White woodland flower" , "perennial" , "Flower; marine creature" .)