A contest between two Poles and an Arab (7)
I believe the answer is:
saracen
'an arab' is the definition.
(Saracen is an example)
'a contest between two poles' is the wordplay.
'contest' becomes 'race' (race is a kind of contest).
'between' means one lot of letters goes inside another.
'two poles' becomes 'sn'.
'a'+'race'='arace'
'arace' placed within 'sn' is 'SARACEN'.
'and' acts as a link.
(Other definitions for saracen that I've seen before include "Arab fighting the Crusades" , "Crusader's foe" , "Old Arab" , "Muslim defender in Crusades" , "old Muslim back" .)