Or a variety of white rose (9)
I believe the answer is:
otherwise
'or a variety' is the definition.
I can't tell whether this definition defines the answer.
'of white rose' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or 'of' the letters).
'white'+'rose'='whiterose'
'whiterose' anagrammed gives 'OTHERWISE'.
Can you help me to learn more?
(Other definitions for otherwise that I've seen before include "Under different conditions" , "As an alternative - like white rose" , "In other respects or ways" , "Alternatively" , "White rose seen in a different way" .)