Portuguese navigator (8)
I believe the answer is:
magellan
'portuguese navigator' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for magellan that I've seen before include "S American strait named for 16th century Portuguese explorer" , "Portuguese navigator who crossed the Pacific" , "Strait between Atlantic and Pacific oceans" , "Major strait between the Atlantic and Pacific" , "Portuguese navgator" .)