One's repeatedly under credit crunch (6)
I believe the answer is:
crisis
'crunch' is the definition.
(thesaurus)
'one's repeatedly under credit' is the wordplay.
'one's' becomes 'is' (roman numeral).
'repeatedly' shows that letters should be duplicated.
'under' says to put letters next to each other.
'credit' becomes 'cr'.
'is' duplicated is 'isis'.
'isis' after 'cr' is 'CRISIS'.
(Other definitions for crisis that I've seen before include "Turning point in illness" , "Serious or crucial situation" , "Turning point in disease" , "Turning point or crux" , "mess" .)