Flummoxed (7)
'flummoxed' is the definition.
('baffle' can be a synonym of 'flummox')
This is the entire clue.
(Other definitions for baffled that I've seen before include "Perplexed" , "Completely mystified" , "Frustrated" , "Confused" .)
(Other definitions for all at sea that I've seen before include "state of confusion" , "Rescuers at Dunkirk were thus" , "Completely confused on voyage?" , "Entire fleet's" , "Bewildered" .)