Who do you suggest?
I can't imagine anyone good will be available in January.
I know you like Kessie.
Kessie would be very high on my wish list, along with his partner at Milan, Bennacer (different but I like both), and I do like Sabitzer even though he's not an orthodox 6, he's versatile and tactically smart, but if that wasn't going to happen (maybe even if it is because I think we need more than one and can ship out both Sissoko and Winks) and we did want to strengthen CM in January, there might be some decent "potential" available from Ligue 1, which is in a bit of a mess because of their TV deal going awol.
I can't believe we walked away from Sangare (raw but buckets of upside potential) at 9mEur, who's now at PSV. And even if he'd not have panned out we'd been in good shape to not lose much at all, might still have even made some regardless.
People like Bissouma and Anguissa have caught the eye this season, and there's a bunch of the next young Bissouma's and Anguissa's knocking around Ligue 1. Players like Camavinga, Kamara (Marseille), Tchouameni, Fofana (Monaco), Guimaraes (Lyon), Thuram (Nice) and there's probably a couple of others - None are polished, finished articles, I'm not convinced all of them will be ultimately good enough for top level, but I think all would available for pretty reasonable fees (some more than others) would represent good value (risk/reward) punts who we could sign if we couldn't get the likes of Kessie, or hopefully as well as.
There's other players dotted around other leagues that are interesting too, Diawra (Roma), Haidara (RBL) Mwepu (RBS - haven't seen enough of him myself to have a rock solid opinion) all worth thinking about - all would be upgrades on Sissoko as a CM.