UK's highest military man? (6)

I believe the answer is:

nelson

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'military man?' is the definition.
(Lord Nelson)

I don't understand the remainder of the clue.

(Other definitions for nelson that I've seen before include "northern town" , "Emma Hamilton's lover, who died in battle on 21 October 1805" , "Nile battle hero" , "Victorious flag officer" , "English naval hero" .)

I've seen this clue in The Sun.

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