Bank on much litter? (6)
I believe the answer is:
farrow
'litter?' is the definition.
(farrowing is a kind of littering)
'bank on much' is the wordplay.
'bank' becomes 'row' (I've seen this in other clues).
'on' says to put letters next to each other.
'much' becomes 'far' (I've seen this in other clues).
'row' put after 'far' is 'FARROW'.
(Other definitions for farrow that I've seen before include "Produce piglets" , "Give birth to piglets" , "Actress" , "Little piggies" , "Litter - very much on bank?" .)