Insect boy picked up beside one road (8)
I believe the answer is:
ladybird
'insect' is the definition.
(ladybird is a kind of insect)
'boy picked up beside one road' is the wordplay.
'boy' becomes 'lad' (lad is a kind of boy**).
'picked up' says the letters should be written in reverse.
'beside' becomes 'by'.
'one' becomes 'i' (Roman numeral).
'road' becomes 'rd' (abbreviation).
'by' backwards is 'yb'.
'lad'+'yb'+'i'+'rd'='LADYBIRD'
(Other definitions for ladybird that I've seen before include "Small round spotted beetle" , "Spotted creature" , "Garden insect" , "imprint" , "that's spotted in gardens" .)