Grateful to be owing money! (8)
I believe the answer is:
indebted
This clue is a double definition.
'grateful' is the first definition.
(I've seen this before)
'owing money' is the second definition.
(I've seen this before)
'to be' is the link.
(Other definitions for indebted that I've seen before include "Owing gratitude to another for help" , "Obligated" , "Owing money, gratitude" , "Under obligation to, for loan or favour" , "Owing gratitude for a favour done" .)