Calm down and pay up (6)
I believe the answer is:
settle
I believe this clue is a double definition.
'calm down' is the first definition.
(thesaurus)
'pay up' is the second definition.
(I've seen this in another clue)
'and' is the link.
(Other definitions for settle that I've seen before include "Become established, make one's home" , "Come to an arrangement with the bench?" , "Long wooden bench with a back" , "get a seat" , "Come to rest or decide an argument" .)