Shelves for books (8)
I believe the answer is:
reserves
This could be a double definition.
'shelves' is the first definition.
Although both the answer and definition are verbs in their -s form, I can't see how they can define each other.
'books' is the second definition.
('reserve' can be a synonym of 'book')
'for' acts as a link.
Can you help me to learn more?
(Other definitions for reserves that I've seen before include "Stockpiles" , "Books" , "group of people for backup?" .)