Not all of lethal force (4)

I believe the answer is:

half

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'not all' is the definition.
I can't judge whether this defines the answer.

'of lethal force' is the wordplay.
'of' indicates the answer is hidden within the clue.
'HALF' is hidden within 'lethal force'.

Can you help me to learn more?

(Other definitions for half that I've seen before include "little drink" , "one over a couple" , "50 per cent" , "Fifty percent" , "proportion" .)

I've seen this clue in The Mirror.

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