Enigmatic poser's a cheat making a fresh start (7)
I believe the answer is:
riddler
'enigmatic poser's' is the definition.
(someone who poses enigmas)
I can't explain the rest of the clue.
(Other definitions for riddler that I've seen before include "Puzzle setter" , "One straining" , "passing on only the finest material?" , "Sphinx?" , "setter of puzzles" .)