Came down and paid up (7)
I believe the answer is:
settled
This clue could be a double definition.
'came down' is the first definition.
(settling is a kind of coming down)
'paid up' is the second definition.
'settled' can be an answer for 'paid' (thesaurus). I am not sure about the 'up' bit.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for settled that I've seen before include "Resolved; calm" , "Resolved (an argument)" , "Colonised; decided" , "Put down roots; decided" , "Agreed; sorted" .)