Sign outside of the man's book (9)
I believe the answer is:
thesaurus
'book' is the definition.
(thesaurus is a kind of book)
'sign outside of the man's' is the wordplay.
'sign' becomes 'taurus' (Taurus is an example).
'outside of' means one lot of letters goes inside another.
'the man's' becomes 'he's' ('he is' means a particular man is).
'taurus' placed around 'hes' is 'THESAURUS'.
(Other definitions for thesaurus that I've seen before include "Reference book" , "storehouse" , "Word book" , "lists?" , "treasury" .)