Road vehicle adopted by one American guy involved in fatal flight (6)
I believe the answer is:
icarus
'guy involved in fatal flight' is the definition.
(figure whose wings melted in Greek mythology)
'road vehicle adopted by one american' is the wordplay.
'road vehicle' becomes 'car' (vehicle driven on the road).
'adopted by' indicates putting letters inside (I've seen this in other clues).
'one' becomes 'i' (Roman numeral).
'american' becomes 'us' (abbreviation for United States).
'i'+'us'='ius'
'car' inserted into 'ius' is 'ICARUS'.
(Other definitions for icarus that I've seen before include "His wings melted when he flew too near the sun" , "Legendary character" , "Son of Daedalus whose wings melted fatally" , "He flew fatally close to the sun in Greek myth" , "Son of Daedalus, who flew too close to the sun" .)