Birds seen on board? (5)
I believe the answer is:
rooks
'birds seen on board?' is the definition.
'rooks' can be an answer for 'birds' (I've seen this before). I am not sure about the 'seen on board?' bit.
This is the entire clue.
(Other definitions for rooks that I've seen before include "Large, crow-like birds" , "Overcharges" , "Fleeces; chessmen" , "Castles, also, in chess" , "Collective name for them is a parliament" .)