Set out with a compass, crossing top of ridge (7)
I believe the answer is:
arrange
'set out' is the definition.
'a compass crossing top of ridge' is the wordplay.
'compass' becomes 'range' ('range' can be a synonym of 'compass'**).
'crossing' indicates putting letters inside.
'top of' indicates taking the first letters.
The first letter of 'ridge' is 'r'.
'range' going around 'r' is 'rrange'.
'a'+'rrange'='ARRANGE'
'with' is the link.
(Other definitions for arrange that I've seen before include "Sort" , "Plan, organize" , "Rare nag (anag.)" , "Dispose" , "Set in order" .)