Meticulous firm on identification and evidence of debts (10)
I believe the answer is:
fastidious
'meticulous' is the definition.
('fastidious' can be similar in meaning to 'meticulous')
'firm on identification and evidence of debts' is the wordplay.
'firm' becomes 'fast' ('fast' can be a synonym of 'firm').
'on' means one lot of letters go next to another.
'identification' becomes 'id'.
'and' says to put letters next to each other.
'evidence of debts' becomes 'ious' (I've seen this in other clues).
'fast'+'id'+'ious'='FASTIDIOUS'
(Other definitions for fastidious that I've seen before include "Meticulous" , "Attentive to detail" .)