Is about to increase bloomers (6)
I believe the answer is:
irises
'bloomers' is the definition.
'is about to increase' is the wordplay.
'about' indicates putting letters inside.
'to increase' becomes 'rise' (rise is a kind of increase).
'is' enclosing 'rise' is 'IRISES'.
(Other definitions for irises that I've seen before include "Eye membranes or showy flowers." , "Parts of eyes or flowering plants" , "Flowers found in the eye" , "Flowers and parts of eyes" , "Subject for van Gogh" .)