Made sure to start washing up (3)
I believe the answer is:
saw
'made sure' is the definition.
('see' can be a synonym of 'make sure')
'start washing up' is the wordplay.
'start' means to remove the last letter (I've seen 'starts' mean this).
'washing' becomes 'wash' (synonyms).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'wash' with its final letter taken off is 'was'.
'was' backwards is 'SAW'.
'to' acts as a link.
(Other definitions for saw that I've seen before include "A maxim with teeth" , "Toothed blade" , "Was turned into a cutting tool" , "item in tool kit" , "Noticed - tool" .)