Gunman's order! (5,2)
I believe the answer is:
hands up
'gunman's order' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hands up that I've seen before include "order to surrender" , "Armed robber's order" , "Don't resist, I've a gun!" , "Who knows" , "Footpad's instruction" .)