Garden bloom (4)
(Other definitions for begonia that I've seen before include "Herbaceous plant whose flowers have no petals" , "Tropical plant" , "Common garden plant" , "bloomer" , "colourful flower" .)
'garden bloom' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for iris that I've seen before include "Circular coloured membrane in the eye" , "Female" , "Garden flower - part of eye" , "Ms Murdoch" , "may open up in camera" .)