City to fight with the Athenians, primarily (6)
I believe the answer is:
sparta
'city' is the definition.
(Sparta is an example)
'fight with the athenians primarily' is the wordplay.
'fight' becomes 'spar' (sparring is a kind of fighting**).
'with' is a charade indicator (letters next to each other).
'primarily' says to take the initial letters.
The first letters of 'the athenians' is 'ta'.
'spar'+'ta'='SPARTA'
'to' is the link.
(Other definitions for sparta that I've seen before include "Ancient Greek city whose citizens were famed for toughness" , "place of austerity" , "austere place" , "Ancient Greek city, capital of Laconia" , "Rival of Athens during the Peloponnesian Wars" .)