South American can start to need car (6)
I believe the answer is:
saloon
'car' is the definition.
(I know that saloon is a type of car)
'south american can start to need' is the wordplay.
'south american' becomes 'SA'.
'can' becomes 'loo' (both can informally mean toilet).
'start to' indicates taking the first letters.
The first letter of 'need' is 'n'.
'sa'+'loo'+'n'='SALOON'
(Other definitions for saloon that I've seen before include "Large public room" , "Car with separate boot" , "Bar room" , "An American pub, as in the wild west" , "Car; public room" .)