Soft skin binding books (6)
I believe the answer is:
flabby
'soft' is the definition.
(I know that soft can be written as flabby)
'skin binding books' is the wordplay.
'skin' becomes 'flay' (flay can mean to take something's skin off).
'binding' is an insertion indicator.
'books' becomes 'bb' (two abbreviations for book).
'flay' placed around 'bb' is 'FLABBY'.
(Other definitions for flabby that I've seen before include "Flaccid" , "More than ample" , "Having soft, loose flesh" , "Saggy" , "lacking vitality" .)