You can check out the exact wording of the reveal below in a tweet from Marvel, but the bottom line is they've got nine episodes to go this season and they're committed to resolving the mystery on the way out.
Fans have speculated that the character could turn out to be any number of Marvel villains, an original character for the show or even some of the S.H.I.E.L.D. high command under Captain America: The Winter Soldier villain Alexander Pierce.
More news from #TCA14- fans will learn the identity of the Clairvoyant in the final 9 episodes of #Marvel's #AgentsofSHIELD season 1!
— Marvel Entertainment (@Marvel) January 17, 2014