Awful trouble you'll have getting the infernal money? (4,2,3)
I believe the answer is:
hell to pay
'awful' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'trouble you'll have getting the infernal money?' is the wordplay.
I cannot really see how this works, but
'trouble' could be 'hell' (hell is a kind of trouble) and 'hell' is found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'money?' could be 'pay' (I've seen this in other clues) and 'pay' is found within the answer.
A single letter 'o' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for hell to pay that I've seen before include "leading to serious consequences" , "dire consequences" .)