Better nominate extraordinary explorer (7,4)
I believe the answer is:
captain cook
'explorer' is the definition.
'better nominate extraordinary' is the wordplay.
I cannot really see how this works, but
'better' could be 'cap' (both can mean to beat somebody else's attempt) and 'cap' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for captain cook that I've seen before include "18th century navigator and explorer" , "New Zealand's charter" , "English explorer, killed in Hawaii" .)