River at Arles (5)
I believe the answer is:
rhone
'river at arles' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rhone that I've seen before include "12 wine region" , "River flowing through Lake Geneva" , "Current" , "Fr. river and wine" , "Major French river, rising in Switzerland" .)