Novel's primary sources of satire concern one overseas pressman (5)
I believe the answer is:
scoop
'novel's' is the definition.
(Evelyn Waugh novel)
'primary sources of satire concern one overseas pressman' is the wordplay.
'primary sources of' says to take the initial letters.
The first letters of 'satire concern one overseas pressman' is 'SCOOP'.
(Other definitions for scoop that I've seen before include "Book by Evelyn Waugh (exclusive)" , "exclusively yours?" , "Kind of ladle or shovel-like tool - reporters seek it" , "Implement for ice cream" , "Hollow concave utensil" .)