Calm down and pay (6)
I believe the answer is:
settle
I believe this clue is a double definition.
'calm down' is the first definition.
(thesaurus)
'pay' is the second definition.
(as in settling a bill)
'and' is the link.
(Other definitions for settle that I've seen before include "Become established and pay debt" , "Bring to an end, agree terms" , "Decide - colonise" , "reach a decision" , "Arrange; colonise" .)