Advancing, supporting conflict, died (7)
I believe the answer is:
forward
'advancing' is the definition.
(I know that advancing can be written as forward)
'supporting conflict died' is the wordplay.
'supporting' becomes 'for' (being for something means supporting it).
'conflict' becomes 'war' (war is a kind of conflict).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'for'+'war'+'d'='FORWARD'
(Other definitions for forward that I've seen before include "Send on; football player" , "going on" , "advance" , "Promote" , "team player" .)