Group of countries meeting slight problem separate (7)
I believe the answer is:
unhitch
'separate' is the definition.
(I've seen this in another clue)
'group of countries meeting slight problem' is the wordplay.
'group of countries' becomes 'UN' (United Nations).
'meeting' says to put letters next to each other.
'slight problem' becomes 'hitch' (a hitch is a problem).
'un'+'hitch'='UNHITCH'
(Other definitions for unhitch that I've seen before include "Unhook, unfasten" , "free?" , "divorce?" , "Part" , "Remove from a harness" .)