Tackle a criminal? Just try! (4,1,2)

I believe the answer is:

have a go

I believe this is a double definition.

'tackle a criminal?' is the first definition.
(I've seen this before)

'just try' is the second definition.
(phrase used to tell someone to try something)

(Other definitions for have a go that I've seen before include "Take a turn" , "Intervening to stop a criminal (colloq,)" , "Try (to help stop criminal?)" , "Words of encouragement" , "Attempt something" .)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app