Credit is doubled in emergency (6)
I believe the answer is:
crisis
'emergency' is the definition.
(thesaurus)
'credit is doubled' is the wordplay.
'credit' becomes 'cr'.
'doubled' says to double the letters.
'is' duplicated is 'isis'.
'cr'+'isis'='CRISIS'
'in' is the link.
(Other definitions for crisis that I've seen before include "Period of dire trouble" , "disaster" , "Turning point in disease" , "Decisive moment, turning point" , "Desperate situation" .)