Outcome sure to upset an officer (6)
I believe the answer is:
result
'outcome' is the definition.
('result' can be a synonym of 'outcome')
'sure to upset an officer' is the wordplay.
'to upset' indicates an anagram.
'an officer' becomes 'lt' (I've seen this in other clues).
'sure' is an anagram of 'resu'.
'resu'+'lt'='RESULT'
(Other definitions for result that I've seen before include "End - issue" , "Effect of lustre" , "Verdict" , "Effect - outcome" , "Outcome of an undertaking" .)