Detective English arrived with one man's book (9)
I believe the answer is:
decameron
'book' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'detective english arrived with one man's' is the wordplay.
'detective english' becomes 'de' (this could be a standard abbreviation which I don't know about).
'arrived' becomes 'came' (coming is a kind of arriving).
'with' is a charade indicator (letters next to each other).
'one man' becomes 'ron' (short for Ronald).
'de'+'came'+'ron'='DECAMERON'
Can you help me to learn more?
(Other definitions for decameron that I've seen before include "Collected tales" , "14th century Italian book of tales" , "Collection of 100 short stories by Boccaccio - rename cod (anag)" , "A hundred tales" , "Boccaccio's tales" .)