Wordbook or dictionary (7)
I believe the answer is:
lexicon
This clue is a double definition.
'wordbook' is the first definition.
(lexicon is a kind of wordbook)
'dictionary' is the second definition.
(I know that lexicon is a type of dictionary)
(Other definitions for lexicon that I've seen before include "Dictionary, especially of ancient languages" , "set of terms" , "Word reference book" , "it has a lot of words" , "Book of words" .)