Swindler runs past new sleuth (7)
I believe the answer is:
hustler
'swindler' is the definition.
(I've seen this before)
'runs past new sleuth' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'past' says to put letters next to each other.
'new' is an anagram indicator.
'sleuth' anagrammed gives 'hustle'.
'r' after 'hustle' is 'HUSTLER'.
(Other definitions for hustler that I've seen before include "Energetic or crooked operator" , "Prostitute" , "Swindler" , "Conman" , "Aggressive dealer" .)