The sailor's fears are disguised (8)
I believe the answer is:
seafarer
'the sailor's' is the definition.
(seafarer is a kind of sailor)
'fears are disguised' is the wordplay.
'disguised' indicates anagramming the letters.
'fears'+'are'='fearsare'
'fearsare' with letters rearranged gives 'SEAFARER'.
(Other definitions for seafarer that I've seen before include "Salt" , "One travelling by ship" , "Traveller over water" , "Sinbad?" , "Jack" .)