Flowers put back in greenhouses, originally (5)
I believe the answer is:
roses
'flowers' is the definition.
(rose is a type of flower)
'back in greenhouses originally' is the wordplay.
'back' is a reversal indicator.
'in' indicates the answer is hidden within the clue.
'sesor' is hidden in the letters of 'greenhouses originally'.
'sesor' reversed gives 'ROSES'.
'put' acts as a link.
(Other definitions for roses that I've seen before include "Thorny plants" , "Occupants of bed" , "Bloomers" , "Beautiful flowers, seen annually in Tralee" , "These flowers in one's cheeks usually denote health" .)