Several books in one vehicle (7)
I believe the answer is:
omnibus
I believe this is a triple definition!
'several books' is the first definition.
(I've seen this before)
'in' is a link.
'one' is the second definition.
(thesaurus)
'vehicle' is the third definition.
(I've seen this before)
(Other definitions for omnibus that I've seen before include "Large public vehicle" , "Book - public transport" , "Compound volume" , "book collection" , "Charabanc" .)