Cause for a lawsuit (4)
I believe the answer is:
tort
'cause for a lawsuit' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tort that I've seen before include "Wrongful act (in law)" , "Small tropical fish" , "Wrongdoing for which damages may be sought" , "Trot after legal wrong liable to damages" , "Trot to get legal wrong" .)