Sailor's small white bowl (4)
I believe the answer is:
jack
'sailor's' is the definition.
(informal term for a sailor)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for jack that I've seen before include "Card -- raiser" , "Target ball in bowls" , "Best Actor Oscar winner 1997, for 'As Good As It Gets'" , "bowler rolls it" , "White bowls target" .)