Ben riding chariot over great lake (5)
I believe the answer is:
huron
'great lake' is the definition.
(I've seen this before)
'ben riding chariot over' is the wordplay.
'ben riding chariot' becomes 'hur' (Ben-Hur).
'over' becomes 'on' (I've seen this in other clues).
'hur'+'on'='HURON'
(Other definitions for huron that I've seen before include "Second largest of the Great Lakes" , "One of the Great Lakes of North America" , "N. American lake" , "Great Lake" .)