Losing head, Scot in car transported drug (8)
I believe the answer is:
narcotic
'drug' is the definition.
(I've seen this before)
'losing head scot in car transported' is the wordplay.
'losing head' means to remove the first letter.
'transported' is an anagram indicator.
'scot'+'in'+'car'='scotincar'
'scotincar' with its first letter removed is 'cotincar'.
'cotincar' with letters rearranged gives 'NARCOTIC'.
(Other definitions for narcotic that I've seen before include "this will induce numbness" , "Sedative" , "Drug producing numbness and stupor" , "(Drug) inducing numbness" , "Drug to induce drowsiness or stupor" .)