Naval hero has grip on opponent (6)
I believe the answer is:
This clue might be a double definition.
'naval hero' is the first definition.
(I've seen this before)
'grip on opponent' is the second definition.
'nelson' can be an answer for 'grip' (I've seen this before). I am unsure of the 'on opponent' bit.
'has' is the link.
Can you help me to learn more?
(Other definitions for nelson that I've seen before include "Admiral; wrestling hold" , "English admiral, mortally wounded at Trafalgar" , "Noted English admiral" , "Admiral on a column" , "English naval hero" .)