Necromancer dismisses con men with runner at the track (5)
I believe the answer is:
racer
'necromancer dismisses con men' is the definition.
I can't tell whether this defines the answer.
'runner at the track' is the wordplay.
'runner' becomes 'r' (abbreviation).
'at' means one lot of letters go next to another (I've seen this in other clues).
'the track' becomes 'race' (I can't justify this - if you can you should believe this answer much more).
'r' put after 'race' is 'RACER'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for racer that I've seen before include "Fast competitive car or animal" , "Runner" , "Athlete" , "One car" , "sportsman" .)