DA taking hat off backwards? Bloomer! (8)
I believe the answer is:
daffodil
'bloomer' is the definition.
(flower which blooms)
'da taking hat off backwards?' is the wordplay.
'taking' is a charade indicator (letters next to each other).
'hat' becomes 'lid' (lid can informally mean a hat).
'backwards?' says the letters should be written backwards (I've seen 'backwards' mean this).
'lid'+'off'='lidoff'
'lidoff' reversed gives 'ffodil'.
'da'+'ffodil'='DAFFODIL'
(Other definitions for daffodil that I've seen before include "Yellow spring flower beloved of Wordsworth" , "Flower from bulb" , "Floral emblem of Wales" , "Plant of the genus Narcissus" , "Flower, emblem of Wales" .)