D-Day beach sergeant's first news (5)
I believe the answer is:
sword
'd-day beach' is the definition.
(Sword Beach was a site of the D-Day landings)
'sergeant's first news' is the wordplay.
'sergeant's first' becomes 's' (1st letter of 'sergeant').
'news' becomes 'word' (synonyms).
's'+'word'='SWORD'
(Other definitions for sword that I've seen before include "Bladed weapon" , "Brand" , "killer?" , "Fencer's weapon" , "Performer whose throat is in danger?" .)