Flowers planted in upturned vases organically (5)
I believe the answer is:
roses
'flowers' is the definition.
(rose is a type of flower)
'planted in upturned vases organically' is the wordplay.
'upturned' says the letters should be written backwards.
'planted in' indicates a hidden word.
'sesor' is hidden in the letters of 'vases organically'.
'sesor' written backwards gives 'ROSES'.
(Other definitions for roses that I've seen before include "Flowers, usually red, pink, white or yellow" , "chocolates" , "the wars" , "Red, white war symbols" , "These flowers in one's cheeks usually denote health" .)