Meet first of chums on border (8)
I believe the answer is:
converge
'meet' is the definition.
(converging is a kind of meeting)
'first of chums on border' is the wordplay.
'first of chums' becomes 'c' (1st letter of 'chums').
'border' becomes 'verge' (verge is a kind of border).
'c'+'on'+'verge'='CONVERGE'
(Other definitions for converge that I've seen before include "Move toward the same point" , "Move or draw together into one place" , "Tend to meet at a point" , "Approach a single point" , "Tend towards a common point" .)