False fiancée ultimately bringing disgrace (5)
I believe the answer is:
shame
'disgrace' is the definition.
(I know that disgrace can be written as shame)
'false fiancee ultimately' is the wordplay.
'false' becomes 'sham' (sham means fake or pretend).
'ultimately' says to take the final letters.
The last letter of 'fiancee' is 'e'.
'sham'+'e'='SHAME'
'bringing' acts as a link.
(Other definitions for shame that I've seen before include "disgraceful" , "Discredit - ignominy" , "Regrettable thing" , "Feeling of humiliation" , "Disgrace, intense regret" .)