Plough on a grave (9)
I believe the answer is:
persevere
'plough' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how one could define the other.
'on a grave' is the wordplay.
'on' means one lot of letters go next to another.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'grave' becomes 'severe' (synonyms).
'per'+'severe' is 'PERSEVERE'.
Can you help me to learn more?
(Other definitions for persevere that I've seen before include "Keep going" , "Remain" , "Serve peer (anag.)" , "give it another try" , "Continue - stick to one's guns" .)