Continue for every grave (9)
I believe the answer is:
persevere
'continue' is the definition.
(I know that persevere is a more specific form of the action continue)
'every grave' is the wordplay.
'every' becomes 'per' ('per' means 'for each' or 'for every').
'grave' becomes 'severe' (synonyms).
'per'+'severe'='PERSEVERE'
'for' is the link.
(Other definitions for persevere that I've seen before include "Remain" , "Persist steadily" , "Struggle on!" , "Steadfastly continue" , "Serve peer (anag.)" .)