A boaster's bloomer (5)
I believe the answer is:
aster
'bloomer' is the definition.
(aster is a kind of flowering plant)
'a boaster's' is the wordplay.
'ASTER' is hidden in amongst the letters.
However, I am unsure how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for aster that I've seen before include "Flower of the daisy family - rates (anag)" , "Plant like a Michaelmas daisy" , "Stare oddly at the flower" , "bloomer" , "Stare at pretty flower" .)