Brave -- ultimately afraid, see, of nobody (4)
I believe the answer is:
defy
'brave' is the definition.
(thesaurus)
'ultimately afraid see of nobody' is the wordplay.
'ultimately' indicates one should take the final letters.
The last letters of 'afraid see of nobody' are 'DEFY'.
(Other definitions for defy that I've seen before include "Flout" , "Resist (someone) openly" , "Brave" , "Withstand" , "Openly resist (authority etc)" .)