Knowing prisoners caught with debts (9)
I believe the answer is:
conscious
'knowing' is the definition.
(thesaurus)
'prisoners caught with debts' is the wordplay.
'prisoners' becomes 'cons' (short for convicts).
'caught' becomes 'c' (cricket abbreviation).
'with' says to put letters next to each other.
'debts' becomes 'IOUs' (promises to pay debts).
'cons'+'c'+'ious'='CONSCIOUS'
(Other definitions for conscious that I've seen before include "Aware of surroundings, sensations and thoughts" , "Having awareness, knowing" , "Having awareness of surroundings" , "Deliberate, intentional" , "Aware, of one's surroundings" .)