Try again - that's the opposite of how this answer goes! (4,2,6,3)
I believe the answer is:
back to square one
'try again' is the definition.
I don't understand the remainder of the clue.
(Other definitions for back to square one that I've seen before include "Illegal pawn move made" , "no further forward?" , "Start from scratch" , "when you'd gone right round the board" , "Having completed a circuit" .)