Watch where you go with leader of killers freed (4,3)

I believe the answer is:

look out

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'watch' is the definition.
(I know that watch can be written as look out)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for look out that I've seen before include "Be watchful" , "Take care" , "Be on your guard!" , "A view of the future" , "makes one be careful!" .)

I've seen this clue in The Independent.

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