Mandela's naval hero (6)
I believe the answer is:
nelson
'naval hero' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for nelson that I've seen before include "Admiral called 5" , "Horatio or Mandela?" , "Maritime chief" , "'Horatio ..., English admiral (6)'" , "English admiral, lover of Lady Hamilton" .)