European and South Australian division are completely different (5,5)
I believe the answer is:
poles apart
'completely different' is the definition.
(I've seen this before)
'european and south australian division' is the wordplay.
'european' becomes 'pole' (Pole is an example).
'and' is a charade indicator (letters next to each other).
'south' becomes 's' (synonyms).
'australian' becomes 'a'.
'division' becomes 'part' (synonyms).
'pole'+'s'+'a'+'part'='POLES APART'
'are' acts as a link.
(Other definitions for poles apart that I've seen before include "Quite opposite" , "Completely different" , "far away from each other?" , "with widely differing views" , "Incompatible" .)