Soldier on for each grave (9)
I believe the answer is:
persevere
'soldier on' is the definition.
(I've seen this before)
'each grave' is the wordplay.
'each' becomes 'per'.
'grave' becomes 'severe' ('severe' can be a synonym of 'grave').
'per'+'severe'='PERSEVERE'
'for' acts as a link.
(Other definitions for persevere that I've seen before include "Keep trying" , "Press on" , "Continue - stick to one's guns" , "Soldier on" , "Carry on regardless" .)