Catastrophe, as foci changed (6)
I believe the answer is:
fiasco
'catastrophe' is the definition.
(I've seen this before)
'as foci changed' is the wordplay.
'changed' indicates an anagram.
'as'+'foci'='asfoci'
'asfoci' is an anagram of 'FIASCO'.
(Other definitions for fiasco that I've seen before include "Utter and ridiculous failure" , "An absolute mess, what a farce" , "Ignominious result" , "Ignominious failure" , "Utter failure, debacle" .)