Out of a book, one fed yarn (6)
I believe the answer is:
abloom
'out' is the definition.
(I've seen this before)
'a book one fed yarn' is the wordplay.
'book' becomes 'b' (abbreviation for book).
'one fed yarn' becomes 'loom' (yarn may be fed through a loom).
'a'+'b'+'loom'='ABLOOM'
'of' acts as a link.
(Other definitions for abloom that I've seen before include "Healthy" , "no longer buddy of Rose?" , "full of colour" , "In flower" , "Flourishing" .)