Pilots remain at sea (6)
I believe the answer is:
airmen
'pilots' is the definition.
(I've seen this before)
'remain at sea' is the wordplay.
'at sea' indicates anagramming the letters.
'remain' with letters rearranged gives 'AIRMEN'.
(Other definitions for airmen that I've seen before include "Male aviators" , "Flyers" , "Red Arrows" , "Daedalus and Icarus for example" , "Some engaged in 7 [NATIONAL SERVICE]" .)