Reserve bank works here (9)
I believe the answer is:
bookshelf
'works here' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'reserve bank' is the wordplay.
'reserve' becomes 'book' (booking is a kind of reserving).
'bank' becomes 'shelf' (I've seen this before).
'book'+'shelf'='BOOKSHELF'
(Other definitions for bookshelf that I've seen before include "A supporter of literature?" , "Library support" , "supporter of literary works" , "Library furniture item" , "It may hold great volumes?" .)