Confused, as Columbus often was? (2,3)
I believe the answer is:
at sea
I believe this clue is a double definition.
'confused' is the first definition.
(synonyms)
'as columbus often was?' is the second definition.
(Christopher Columbus often went to sea)
(Other definitions for at sea that I've seen before include "Having difficulty understanding" , "'Filled with bewilderment (2,3)'" , "on board" , "Sailing on a ship?" , "cruising?" .)