What "will be" will be (3)
I believe the answer is:
are
'what will be will be' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for are that I've seen before include "(We/they/you) exist" , "(They/you/we) exist" , "is for more than one" , "Unit of land measure equal to 100 square metres" , "live" .)