Clean down (5)
I believe the answer is:
preen
This clue might be a double definition.
'clean' is the first definition.
(preening is a kind of cleaning)
'down' is the second definition.
The definition and answer can be both to do with contact as well as being verbs in their base form.
Perhaps there's an association between them I don't understand?
Can you help me to learn more?
(Other definitions for preen that I've seen before include "setdown straight?" , "Beautify" , "Titivate oneself" , "(Of a bird) tidy and clean feathers" , "to give himself a pat on the back" .)