Do-over, of a sort (3)
I believe the answer is:
let
'do-over of a sort' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for let that I've seen before include "Allow or lease" , "inefficient service" , "Allow - hire" , "Reason for scrubbing service" , "Rent out: grant" .)