Settle a king on mountain chain (7)
I believe the answer is:
arrange
'settle' is the definition.
(I've seen this before)
'a king on mountain chain' is the wordplay.
'a king' becomes 'ar' (I've seen this in other clues**).
'on' means one lot of letters go next to another.
'mountain chain' becomes 'range' ('range' can be a synonym of 'mountain chain').
'ar'+'range'='ARRANGE'
(Other definitions for arrange that I've seen before include "Put in neat order" , "Orchestrate - order" , "Bring about or put in order" , "Put in order; make plans" , "Put in systematic order" .)