Seaman in a hold (6)
I believe the answer is:
nelson
'a hold' is the definition.
(wrestling hold)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for nelson that I've seen before include "Maritime chief" , "English admiral, lover of Lady Hamilton" , "Admiral; wrestling hold" , "Naval hero who died at Trafalgar" , "Victorious flag officer" .)