Marine brought into A&E died with weapon (5)
I believe the answer is:
armed
'with weapon' is the definition.
'marine brought into ae died' is the wordplay.
'marine' becomes 'rm'.
'brought into' indicates putting letters inside.
'died' becomes 'd'.
'rm' placed within 'ae' is 'arme'.
'arme'+'d'='ARMED'
(Other definitions for armed that I've seen before include "Tooled up" , "ready to fight" , "equipped for fighting" , "Supplied with weapons" , "Prepared for battle" .)