Ulster’s remarkable outcome (6)
I believe the answer is:
result
'outcome' is the definition.
(I know that outcome can be written as result)
'ulster's remarkable' is the wordplay.
'remarkable' indicates anagramming the letters.
'ulster' is an anagram of 'RESULT'.
(Other definitions for result that I've seen before include "Ulster (anag) - outcome" , "End - issue" , "Final score" , "Final outcome" , "Verdict" .)