A segment of Horatio Nelsons speech (7)
I believe the answer is:
oration
'speech' is the definition.
(oration is a kind of speech)
'a segment of horatio nelsons' is the wordplay.
'a segment of' indicates the answer is hidden within the clue (I've seen this in other clues).
'ORATION' is hidden in the letters of 'horatio nelsons'.
(Other definitions for oration that I've seen before include "Platform speech" , "A public or ceremonial speech" , "Power of speech" , "An eloquent speech" , "lecture" .)