Make certain, rejecting right result (5)
I believe the answer is:
ensue
'result' is the definition.
(to ensue is to occur or result)
'make certain rejecting right' is the wordplay.
'make certain' becomes 'ensure' (synonyms).
'rejecting' is a deletion indicator.
'right' becomes 'r' (common abbreviation).
'ensure' with 'r' taken out is 'ENSUE'.
(Other definitions for ensue that I've seen before include "Come to pass" , "Proceed" , "Happen as consequence or afterward" , "Follow later" , "Happen or come about as consequence" .)