Board of Unilever implementing joint agreement initially (5)
I believe the answer is:
ouija
'board' is the definition.
(I know that Ouija is a type of board)
'of unilever implementing joint agreement initially' is the wordplay.
'initially' indicates taking the first letters.
The first letters of 'of unilever implementing joint agreement' is 'OUIJA'.
(Other definitions for ouija that I've seen before include "(Seance) lettered board" , "Board able to answer questions?" , "This board is used by spiritualists and seances" , "Type of board used in seances" , "This board is used in spiritualistic sessions" .)