Free book prefaces with a line of The Woman in White? (6)
I believe the answer is:
bridal
'the woman in white?' is the definition.
(I've seen this before)
'free book prefaces with a line' is the wordplay.
'free' becomes 'rid' (to be free of something is to be rid of it).
'book' becomes 'b' (abbreviation for book).
'prefaces' means one lot of letters go next to another (some letters go before others).
'with' is a charade indicator (letters next to each other).
'line' becomes 'l' (used when specifying particular lines from a poem).
'rid' put after 'b' is 'brid'.
'brid'+'a'+'l'='BRIDAL'
'of' is the link.
(Other definitions for bridal that I've seen before include "Relating to the woman getting married" , "Woman in White" , "Newly-wed" , "Wedding's" , "To do with wedding - perhaps a suite" .)