Back during terrible rains, owing money (2,7)
I believe the answer is:
in arrears
'owing money' is the definition.
'in arrears' can be an answer for 'owing' (I've seen this before). I'm not sure about the 'money' bit.
'back during terrible rains' is the wordplay.
'back' becomes 'rear' (something's rear is its back).
'during' is an insertion indicator.
'terrible' indicates an anagram.
'rains' with letters rearranged gives 'inars'.
'rear' going inside 'inars' is 'IN ARREARS'.
Can you help me to learn more?
(Other definitions for in arrears that I've seen before include "Behindhand (with rent)" , "Position when a debt remains unpaid after its due date" , "Owing" , "Rare rains beyond the due time" , "Late with payments" .)