Extensive evidence of debt acquired by police officers (7)
I believe the answer is:
copious
'extensive' is the definition.
(synonyms)
'evidence of debt acquired by police officers' is the wordplay.
'evidence of debt' becomes 'iou' (an IOU, 'I owe you').
'acquired by' is an insertion indicator.
'police officers' becomes 'cops' (cop is a kind of police officer).
'iou' inserted into 'cops' is 'COPIOUS'.
(Other definitions for copious that I've seen before include "great supply?" , "Many" , "Large in number or quantity" , "Plentiful, existing in large amounts" , "Redundant" .)