One's taken over a board game -— Othello he couldn't stand (4)
I believe the answer is:
iago
'othello he couldn't stand' is the definition.
(Iago hates Othello in Shakespeare's play)
'one's taken over a board game' is the wordplay.
'one' becomes 'i' (Roman numeral).
'taken' is a charade indicator (letters next to each other).
'over' is a charade indicator (letters next to each other).
'board game' becomes 'go' (go is a kind of board game).
'i'+'a'+'go'='IAGO'
(Other definitions for iago that I've seen before include "Othello's enemy" , "Advisor to soldier" , "stage villain" , "Othello's Ancient" , "villainous ensign" .)