Fifth in Crufts, I'm amazed obedient dog moped, say (3-7)
I believe the answer is:
two-wheeler
'moped say' is the definition.
(I know that moped is a type of two-wheeler)
'fifth in crufts i'm amazed obedient dog' is the wordplay.
'fifth in crufts' becomes 't' (5th letter of 'crufts').
'i'm amazed' becomes 'wow'.
'obedient dog' becomes 'heeler' (I've seen this in another clue).
't'+'wow'+'heeler'='TWO-WHEELER'
(Other definitions for two-wheeler that I've seen before include "Vehicle such as bicycle, moped etc" , "Bike or motorcycle" .)