"You're a crooked jerky jockey, and you drive a crooked hoss!" -- What's a Hoss?
Solution 1:
hoss [OXD]
nonstandard spelling of horse, used to represent dialect or informal speech
drive [OXD]
4.2 Force (someone) to work to an excessive extent.
Solution 2:
“Hoss” certainly means “horse” here.
The same simplification of /rs/ to /s/ has occurred in a number of other words (often in informal or dialectal forms): cuss for curse, apparently the verb bust for burst, and American English ass for arse (the form arse seems to have pretty much gone extinct in American English).