“Nonsense!” a woman journalist laughed loudly (8)
I believe the answer is:
guffawed
'laughed loudly' is the definition.
('guffaw' can be a synonym of 'laugh loudly')
'nonsense a woman journalist' is the wordplay.
'nonsense' becomes 'guff' (I've seen this before).
'woman' becomes 'W' (abbreviation eg in Woman Police Constable).
'journalist' becomes 'ed' (short for editor).
'guff'+'a'+'w'+'ed'='GUFFAWED'
(Other definitions for guffawed that I've seen before include "Roared" , "Laughed loudly" , "Was amused" , "Gave coarse noisy laugh" .)