Puts one's foot down and makes an impression (6)
I believe the answer is:
stamps
'makes an impression' is the definition.
The answer and definition can be both to do with motion as well as being verbs in their -s form.
Perhaps there's a link between them I don't understand?
'puts one's foot down' is the wordplay.
I cannot really see how this works, but
'one's' could be 'am' ('one is' can humorously mean 'I am') and 'am' is present in the answer.
This explanation may well be incorrect...
'and' acts as a link.
Can you help me to learn more?
(Other definitions for stamps that I've seen before include "Items of interest to a philatelist" , "Philatelist's interest" , "Philatelists study them" , "Gummed receipts of postal fees" , "creates an impression" .)