Poor overwhelmed by a cut in payment (9)
I believe the answer is:
allowance
'payment' is the definition.
(allowance is a kind of payment)
'poor overwhelmed by a cut' is the wordplay.
'poor' becomes 'low' (similar in meaning).
'overwhelmed by' indicates putting letters inside (I've seen this in other clues).
'cut' becomes 'lance' (I've seen this before).
'a'+'lance'='alance'
'low' placed inside 'alance' is 'ALLOWANCE'.
'in' acts as a link.
(Other definitions for allowance that I've seen before include "discount" , "Call on with awe for pocket-money or other grant" , "Permissible difference or amount" , "Ocean wall (anag.)" , "Concession - money for expenses" .)