Only part of lethal force (4)

I believe the answer is:

half

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'only part' is the definition.
'half' can be an answer for 'part' (thesaurus). I am unsure of the 'only' bit.

'of lethal force' is the wordplay.
'of' indicates a hidden word.
'HALF' is hidden within 'lethal force'.

Can you help me to learn more?

(Other definitions for half that I've seen before include "Short distance - steal!" , "0.5" , "alcoholic drink" , "one over a couple" , "Wife the better one (joc.)" .)

I've seen this clue in The Mirror.

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