An Arab in a contest between Poles (7)
I believe the answer is:
saracen
'an arab' is the definition.
(I know that Saracen is a type of arab)
'a contest between poles' is the wordplay.
'contest' becomes 'race' (race is a kind of contest).
'between' indicates putting letters inside.
'poles' becomes 'SN' (North and South poles).
'a'+'race'='arace'
'arace' placed inside 'sn' is 'SARACEN'.
'in' acts as a link.
(Other definitions for saracen that I've seen before include "Ear scan (anag.)" , "Opponent of the Crusaders" , "Muslim defender in Crusades" , "Arab fighting the Crusades" , "old Muslim back" .)