Horatio ..., British admiral (6)
I believe the answer is:
nelson
I believe this is a double definition.
'horatio' is the first definition.
(I know that horatio can be written as Nelson)
'british admiral' is the second definition.
(I've seen this before)
(Other definitions for nelson that I've seen before include "English admiral, mortally wounded at Trafalgar" , "Admiral; wrestling hold" , "Nile battle hero" , "Victorious flag officer" , "'Horatio ..., English admiral (6)'" .)