1.
To do the washing-up means to wash the plates, cups, cutlery, and pans which have been used for cooking and eating a meal. ( BRIT; in AM, use wash the dishes )
Martha volunteered to do the washing-up.
N-UNCOUNT
2.
Washing-up is the plates, cups, cutlery, and pans which you have to wash after a meal. ( BRIT; in AM, use dirty dishes , the dishes )
...a brimming bowl of washing-up.
N-UNCOUNT