Conflict over one point causes mistrust (8)
I believe the answer is:
wariness
'mistrust' is the definition.
(thesaurus)
'conflict over one point' is the wordplay.
'conflict' becomes 'war' (war is a kind of conflict).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'one' becomes 'i' (Roman numeral).
'point' becomes 'ness' (ness can mean a geographical point).
'war'+'i'+'ness'='WARINESS'
'causes' acts as a link.
(Other definitions for wariness that I've seen before include "State of caution" , "Circumspection" , "Caution, watchfulnes" .)