Flower a stupid sheep turned over (9)
I believe the answer is:
amaryllis
'flower' is the definition.
(I've seen this before)
'a stupid sheep turned over' is the wordplay.
'stupid' becomes 'silly' (I've seen this before**).
'sheep' becomes 'ram' (ram is a kind of sheep).
'turned over' is a reversal indicator.
'silly'+'ram'='sillyram'
'sillyram' reversed gives 'maryllis'.
'a'+'maryllis'='AMARYLLIS'
(Other definitions for amaryllis that I've seen before include "Trumpet-flowered bulb" , "Showy bulbous plant" , "Lily-like plant" , "Bulbous plant with trumpet-shaped flowers" , "belladonna lily brought this about" .)