Bizarre top, one worn, is choice (6)
I believe the answer is:
option
'is choice' is the definition.
(I've seen this before)
'bizarre top one worn' is the wordplay.
'bizarre' indicates anagramming the letters.
'one' becomes 'I' (Roman numeral).
'worn' becomes 'on' ().
'top' with letters rearranged gives 'opt'.
'opt'+'i'+'on'='OPTION'
(Other definitions for option that I've seen before include "Possible choice" , "The choice of taking or leaving" , "possibility" , "Potion (anag.)" , "Freedom to choose" .)