Bedding plant: a big one unfortunately (7)
I believe the answer is:
begonia
'bedding plant' is the definition.
'begonia' can be an answer for 'plant' (begonia is a kind of plant). I am not sure about the 'bedding' bit.
'a big one unfortunately' is the wordplay.
'unfortunately' indicates anagramming the letters (a bad or unfortunate spelling).
'a'+'big'+'one'='abigone'
'abigone' with letters rearranged gives 'BEGONIA'.
Can you help me to learn more?
(Other definitions for begonia that I've seen before include "Common garden plant" , "colourful flower" , "Herbaceous plant whose flowers have no petals" , "bloomer" , "Tropical plant" .)