Flatten a fellow journalist (8)
I believe the answer is:
pressman
'journalist' is the definition.
(I know that pressman is a type of journalist)
'flatten a fellow' is the wordplay.
'flatten' becomes 'press' (pressing is a kind of flattening).
'a fellow' becomes 'man' (fellow can mean a man).
'press'+'man'='PRESSMAN'
(Other definitions for pressman that I've seen before include "Male journalist" , "correspondent?" .)