Forecast of journalists, mostly very old (8)
I believe the answer is:
presaged
'forecast' is the definition.
(I've seen this before)
'journalists mostly very old' is the wordplay.
'journalists' becomes 'press' (the press can mean the newspaper industry).
'mostly' means to remove the last letter (most but not all of the word).
'very old' becomes 'aged' (I've seen this before).
'press' with its final letter taken off is 'pres'.
'pres'+'aged'='PRESAGED'
'of' acts as a link.
(Other definitions for presaged that I've seen before include "Forecast" , "Foresaw - red pages (anag)" , "Foreshadowed, was an advance sign of" , "Foreseen" , "predicted" .)