White bra, at least, almost undone (9)
I believe the answer is:
alabaster
'white' is the definition.
(alabaster is a kind of white)
'bra at least almost undone' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'undone' indicates an anagram.
'bra'+'at'+'least'='braatleast'
'braatleast' with its last letter taken away is 'braatleas'.
'braatleas' with letters rearranged gives 'ALABASTER'.
(Other definitions for alabaster that I've seen before include "Stab a real odd white mineral" , "Form of gypsum used for carving" , "White gypsum used for carving" , "White stone carved into ornaments" , "Carved form of gypsum" .)