Sailors at work made boast (4)
I believe the answer is:
crew
'sailors' is the definition.
(as in a ship's crew)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for crew that I've seen before include "A kind of short cut" , "Cox and Co" , "Train team" , "Boat's workers" , "Work gang" .)