Journalists housed in well-known block for writers
I believe the answer is:
notepad
'block for writers' is the definition.
(a block is another term for a pad of paper)
'journalists housed in well-known' is the wordplay.
'journalists' becomes 'pa' (Press Association).
'housed in' indicates putting letters inside.
'well known' becomes 'noted' (I've seen this before).
'pa' inserted inside 'noted' is 'NOTEPAD'.
(Other definitions for notepad that I've seen before include "PC" , "Where memos get written" , "Tablet" , "Block writer might have" , "Small block of writing paper" .)