One in road moved fast (5)
I believe the answer is:
raced
'moved fast' is the definition.
'raced' can be an answer for 'moved' (racing is a kind of moving). I'm unsure of the 'fast' bit.
'one in road' is the wordplay.
'one' becomes 'ace' (ace has a value of one in some card games).
'in' is an insertion indicator.
'road' becomes 'rd' (abbreviation for road).
'ace' inserted into 'rd' is 'RACED'.
Can you help me to learn more?
(Other definitions for raced that I've seen before include "Went fast" , "Sped" , "Rushed" , "Went quickly round" , "bolted" .)