Result of a terrible feat (4)
I believe the answer is:
fate
'result' is the definition.
(thesaurus)
'a terrible feat' is the wordplay.
'a terrible' indicates anagramming the letters.
'feat' anagrammed gives 'FATE'.
'of' is the link.
(Other definitions for fate that I've seen before include "Inevitable destiny" , "Predetermined end" , "E.g. Clotho, Atropos" , "Lot -- doom" , "Clotho, Lachesis or Atropos" .)