Make one's case (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
argue
'make one's case' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for argue that I've seen before include "Disagree violently" , "Dispute, bicker" , "Quarrel, row" , "Bandy words" , "Debate, row" .)