Many a new driver (4)
I believe the answer is:
teen
'many a new driver' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for teen that I've seen before include "Juvenile" , "Youngster over twelve" , "Young person" , "Adolescent, then adult-to-be" , "Of 13 to 19 year olds" .)