Some beer for man on board (7)
I believe the answer is:
draught
I believe this is a double definition.
'some beer' is the first definition.
(draught beer is a type of beer)
'man on board' is the second definition.
(a piece in the game draughts)
'for' acts as a link.
(Other definitions for draught that I've seen before include "Water depth; served from a cask" , "Depth of a ship in the water" , "it's felt, when short of cash" , "Too much air - not bottled" , "intake" .)