That quiet, bookish Yank? (8)
I believe the answer is:
american
'yank?' is the definition.
(yank is a kind of American)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for american that I've seen before include "''The Quiet . . . . . . . .'' - Graham Greene" , "Person from the States" , "Main race confused in USA" , "Main race (anag.)" , "Film starring Kevin Spacey" .)