Large betting account, one with admissions of debt (8)
I believe the answer is:
spacious
'large' is the definition.
('spacious' can be a synonym of 'large')
'betting account one with admissions of debt' is the wordplay.
'betting' becomes 'sp'.
'account' becomes 'ac'.
'one with' means one lot of letters go next to another.
'admissions of debt' becomes 'ious' (I've seen this in other clues).
'sp'+'ac'+'ious'='SPACIOUS'
(Other definitions for spacious that I've seen before include "Roomy, not congested" , "Roomy or expansive" , "Ample, roomy" , "Having plenty of room" , "Big and roomy" .)