Hide evidence of debts — that's mad (7)
I believe the answer is:
furious
'mad' is the definition.
(thesaurus)
'hide evidence of debts' is the wordplay.
'hide' becomes 'fur' (animal fur).
'evidence of debts' becomes 'IOUs' (IOU's or I Owe You's).
'fur'+'ious'='FURIOUS'
'that's' is the link.
(Other definitions for furious that I've seen before include "how creditor feels?" , "Enraged" , "Seeing red" , "at boiling point" , "Livid" .)