Blooming awful rates! (5)
I believe the answer is:
aster
'blooming' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'awful rates' is the wordplay.
'awful' indicates anagramming the letters.
'rates' with letters rearranged gives 'ASTER'.
Can you help me to learn more?
(Other definitions for aster that I've seen before include "Flower of the daisy family - rates (anag)" , "Showy garden flower" , "Large daisy" , "Garden plant" , "(Starlike) flower" .)