NCO needing a lot of books after material (8)
I believe the answer is:
sergeant
'nco' is the definition.
(I've seen this before)
'a lot of books after material' is the wordplay.
'lot of books' becomes 'nt' (New Testament).
'after' means one lot of letters go next to another.
'material' becomes 'serge' (serge is a kind of material).
'a'+'nt'='ant'
'ant' after 'serge' is 'SERGEANT'.
'needing' acts as a link.
(Other definitions for sergeant that I've seen before include "Pepper, say" , "Copper" , "Estrange (anag)" , "Reagents (anag)" , "Man in charge" .)