Tiresome fellow with evidence of debt (7)
I believe the answer is:
tedious
'tiresome' is the definition.
('tedious' can be a synonym of 'tiresome')
'fellow with evidence of debt' is the wordplay.
'fellow' becomes 'ted' (I've seen this in other clues).
'with' means one lot of letters go next to another.
'evidence of debt' becomes 'ious' (IOU's or I Owe You's).
'ted'+'ious'='TEDIOUS'
(Other definitions for tedious that I've seen before include "drab" , "Boring, monotonous" , "awfully boring" , "Dull as ditchwater" , "Banal" .)