Looked happy, having got a long way in South Dakota (6)
I believe the answer is:
smiled
'looked happy' is the definition.
(I've seen this before)
'a long way in south dakota' is the wordplay.
'a long way' becomes 'mile' (I've seen this in other clues).
'in' means one lot of letters goes inside another.
'south dakota' becomes 'sd' (abbreviation).
'mile' inserted into 'sd' is 'SMILED'.
'having got' acts as a link.
(Other definitions for smiled that I've seen before include "Grinned" , "drank whisky" , "Looked happy" , "Assumed facial expression indicating pleasure" , "Showed pleasure" .)