Lexicographical publication, old, old manuscript (5)
I believe the answer is:
codex
'old manuscript' is the definition.
(historical form of book)
'lexicographical publication old' is the wordplay.
'lexicographical publication' becomes 'COD' (Concise Oxford Dictionary).
'old' becomes 'ex' (prefix meaning former or onetime).
'cod'+'ex'='CODEX'
(Other definitions for codex that I've seen before include "Volume of ancient manuscripts" , "Book of ancient manuscripts" .)