Males rise after a single bloomer (7)
I believe the answer is:
anemone
'bloomer' is the definition.
(anemone is a kind of flowering plant)
'males rise after a single' is the wordplay.
'males' becomes 'men' (man is a kind of male).
'rise' is a reversal indicator.
'after' is a charade indicator (letters next to each other).
'single' becomes 'one' (a single thing - only one).
'men' reversed gives 'nem'.
'nem' put after 'a' is 'anem'.
'anem'+'one'='ANEMONE'
(Other definitions for anemone that I've seen before include "Plant of the buttercup family - one name (anag)" , "Flower; marine polyp" , "climbing plant" , "Woodland plant - marine polyps" , "The flower is no enema" .)