Tries, with "at" (3,1,2)
I believe the answer is:
has a go
'tries with at' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for has a go that I've seen before include "Attempts to stop a criminal" , "In modern jargon, makes an effort, gives it a shot" , "Confronts criminal" .)