To right a wrong (4)
I believe the answer is:
tort
'a wrong' is the definition.
(legal term)
'to right' is the wordplay.
'right' becomes 'rt' (**).
'to'+'rt'='TORT'
(Other definitions for tort that I've seen before include "Legal wrong or injury" , "Trot after legal wrong liable to damages" , "Act for which damages can be claimed" , "Trot to get legal wrong" , "A legal wrong open to claim for damages" .)