Youth left at the side of the road? (3)
I believe the answer is:
lad
'youth' is the definition.
(lad means a young man)
'left at the side of the road?' is the wordplay.
'left' becomes 'l' (common abbreviation).
'at the side of' means one lot of letters go next to another.
'the road?' becomes 'ad' (I am not sure about this - if you are sure you should believe this answer much more).
'l'+'ad'='LAD'
Can you help me to learn more?
(Other definitions for lad that I've seen before include "Chap, fellow" , "Youngster" , "Son" , "Scottish lover" , "Boy, young man" .)