Fish on board? (5)
I believe the answer is:
skate
I believe this is a double definition.
'fish' is the first definition.
(skate is a kind of fish)
'board?' is the second definition.
(skate board is a kind of board)
'on' is the link.
(Other definitions for skate that I've seen before include "current collector" , "Recite Keats badly to the fish" , "cross ice" , "Type of ray" , "Flat fish" .)