Getting ready to drop litter? (2,3)
I believe the answer is:
Here is my best explanation:
'getting ready to drop' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'litter?' is the wordplay.
I cannot really understand how this works, but
'litter?' could be 'pup' (pupping is a kind of littering) and 'pup' is found within the answer.
The remaining letters 'in' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
(Another definition for in pup that I've seen is "About to drop".)