Finalized (4,2)
(Other definitions for sewn up that I've seen before include "Mended completely - successfully negotiated" , "Satisfactorily completed" , "Successfully completed" .)
'finalized' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for set that I've seen before include "Put, coagulate" , "'Put, place or fix in position (3)'" , "See 16 Down" , "Fix in place; similar group" , "box?" .)