Big top's raised covering debts (8)
I believe the answer is:
spacious
'big' is the definition.
(I've seen this before)
'top's raised covering debts' is the wordplay.
'top's' becomes 'caps' (cap is a kind of top**).
'raised' says the letters should be written in reverse.
'covering' says to put letters next to each other (on top of in down clue).
'debts' becomes 'ious'.
'caps' back-to-front is 'spac'.
'spac'+'ious'='SPACIOUS'
(Other definitions for spacious that I've seen before include "Roomy, not congested" , "Roomy or expansive" , "wide-ranging" , "Big and roomy" , "Having plenty of room" .)