Part of which, essentially, that's like Othello in certain ways (5)
I believe the answer is:
chess
'that's like othello in certain ways' is the definition.
(chess and Othello are both board games)
'part of which essentially' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'CHESS' is hidden in the letters of 'which essentially'.
(Other definitions for chess that I've seen before include "Benny Andersson and Bjorn Ulvaeus musical" , "Game involving mates" , "A game of skill" , "form of battle" , "This is played on board" .)